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Which Choice Most Logically Completes the Text

This is the most recognizable question stem in the Reading and Writing section. A passage builds an argument, stops mid-thought, and asks which choice most logically completes the text. The correct ending is always assembled from parts the passage already gave you, never from outside knowledge.

The rule

The correct completion combines what the passage already stated and adds no new facts.

Read the passage once and identify its structure before the blank. Most of these follow one of a few shapes: a general belief followed by a finding that complicates it, a described experiment followed by its implication, or two facts that together point at a conclusion neither states alone. Naming the shape tells you what kind of ending is needed.

Then predict. Finish the sentence in your own words, even roughly. The prediction does not have to match the correct choice in wording, and it usually will not. Its job is to stop you from evaluating four polished sentences with no reference point, which is when plausible-sounding wrong answers do their damage.

Check each choice for information that came from nowhere. A choice that introduces a cause the passage never mentioned, a comparison to a group never discussed, or a motive never stated is out, even if it is the most reasonable thing you can imagine being true. The standard is whether the passage supports it, not whether it is plausible in the world.

Watch for choices that restate the passage rather than conclude from it. If the passage says a technique reduced errors in trials and the choice says the technique reduced errors in trials, nothing has been inferred. The ending needs to combine the pieces into something the passage implies but did not say outright.

When you are down to two, compare them on three axes: direction, which the transition words fix, scope, meaning how broadly the claim reaches, and certainty, meaning how strongly it is stated. One of the two will be off on at least one of those axes, and that is your elimination.

The trap

Choosing an ending that is reasonable in the real world but requires a fact or assumption the passage never provides.

Try it

Try one
Real question

A statistical model predicts a city's electricity demand from the previous day's temperature, fitted as a straight line through some three thousand six hundred daily observations. Engineer Marisol Quijano notes that the model was fitted using data from a decade in which the city had almost no air conditioning, and that air conditioning is now installed in four households out of five. The relationship between temperature and demand in a city with widespread air conditioning is known to be different in kind, not merely in degree: past a threshold the curve bends sharply instead of rising steadily. She concludes that applying the model to the city today ______

Which choice most logically completes the text?

A lake's fish population can be estimated by marking a sample of fish, releasing them, and later recording what fraction of a second catch carries marks. The method assumes marked fish mix evenly back into the population. Limnologist Rangi Hikuroa clipped a fin on five hundred fish and released them all from one jetty. Tracking a subset that also carried small tags, he found that marked fish in one lake remained clustered near the release point for weeks, and the second catch was taken there, where one fish in three carried a mark. His finding implies that the resulting estimate ______

Which choice most logically completes the text?

  • A) is too low, since too few marked fish were recaptured in the second catch overall.
  • B) is accurate, since the marked fish sample was large enough to provide reliable recapture data.
  • C) is too low, since the second catch contained an unrepresentatively high fraction of marked fish. ✓
  • D) is too high, since the marked fish were clustered and not evenly mixed throughout the population.

Why: The method assumes marked fish mix evenly back into the population, but the tagged subset stayed clustered near the jetty and the second catch was taken there, where one fish in three carried a mark. An inflated marked share makes the population look smaller than it is, so the estimate "is too low, since the second catch contained an unrepresentatively high fraction of marked fish." Answering that it "is too high, since the marked fish were clustered and not evenly mixed throughout the population." names the right cause with the wrong direction: clustering at the sampling spot raises the marked fraction, which pushes the estimate down. Answering that it "is too low, since too few marked fish were recaptured in the second catch overall." has the recapture backwards, since one in three is an unusually high marked fraction, not too few. Answering that it "is accurate, since the marked fish sample was large enough to provide reliable recapture data." rests on sample size, which the passage never questions; the problem is where the marked fish were, not how many were marked.

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Questions students ask

How is this different from a main idea question?

A main idea question asks what the passage says. This one asks what follows from what the passage says. A choice that simply restates a sentence from the text is usually correct on a main idea question and usually wrong here.

Can I use background knowledge about the topic?

No, and it actively hurts. If you know something about the subject, you may accept a choice your knowledge supports while the passage does not. Answer as if the passage is the only source of information you have.

Guides that cover this

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