Question 157·Easy·Words in Context
Marine biologist Dr. Lila Grant points out that coral reefs, once thought to be resilient, are now so _____ that a single heatwave can devastate entire ecosystems.
Which choice completes the text with the most logical and precise word or phrase?
For SAT Words-in-Context questions, always start by fully understanding the sentence without looking at the choices: identify contrasts (like "once thought" vs. "now"), cause-and-effect clues, and whether the tone is positive or negative. Then, plug each choice into the blank and ask, “Does this make the sentence logical and consistent, or does it create a contradiction?” Eliminate choices that don’t fit the meaning or tone, even if they are familiar words, and select the one that best captures the specific idea expressed by the surrounding context.
Hints
Notice the contrast word
Pay attention to the phrase "once thought to be resilient"—the blank should show how the current condition of coral reefs contrasts with that earlier belief.
Focus on the result after the blank
Look closely at what happens because of the condition in the blank: "a single heatwave can devastate entire ecosystems." What kind of condition would allow that to happen?
Check whether the description is positive or negative
Decide if the sentence is describing a strong, safe situation or a risky, worrying one, and eliminate any answer choices that do not match that overall tone.
Plug in each option
Try placing each answer choice in the blank and see which one makes the sentence logically consistent and free of contradictions.
Step-by-step Explanation
Understand the sentence setup
Read the whole sentence: coral reefs were "once thought to be resilient" but now they are so _____ that a single heatwave can devastate entire ecosystems.
The key idea is a contrast between what people used to think (strong, resilient) and what is true now (the opposite condition).
Use the cause-and-effect clue
Focus on the part after the blank: "that a single heatwave can devastate entire ecosystems."
If one heatwave can cause such massive damage, the reefs are clearly in a dangerous, easily harmed state, not a safe or protected one. The word in the blank must match this idea and maintain the negative, worried tone.
Test each answer choice in the sentence
Now plug in each option:
- A) invulnerable: "so invulnerable that a single heatwave can devastate" is a contradiction; if something is invulnerable, it cannot be devastated.
- B) stagnant: means not moving or changing; this does not explain why a single heatwave can destroy ecosystems.
- C) abundant: means existing in large numbers, which says nothing about being harmed by heatwaves.
- D) fragile: "so fragile that a single heatwave can devastate" fits perfectly: it shows that the reefs are easily damaged, matching both the contrast with "resilient" and the idea that one event can cause huge destruction.
So the best and most precise choice is D) fragile.