Free SAT Practice Question

Question 1 of 1
ID: DSAT-RW-81
Section: Digital SAT Reading & Writing (RW) - Broadly Reading - Information and Ideas
Topic: Central Ideas and Details
Difficulty level: Hard

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In 1916, Albert Einstein predicted that accelerating massive objects would send ripples through spacetime—gravitational waves. For decades the idea remained unverified. In 2015, researchers with the Laser Interferometer Gravitational-Wave Observatory (LIGO) reported a distinctive "chirp" recorded almost simultaneously at two facilities. Ultra-stable lasers measured infinitesimal changes in the distance between suspended mirrors, changes consistent with two black holes merging over a billion light-years away. The matching signals ruled out local noise and provided the first direct observation of gravitational waves.

Which choice best states the main idea of the text?

AScientists achieved the first direct detection of gravitational waves, offering the strongest evidence yet for Einstein's prediction.

BScientists have developed a laser-based technique that can study nearly all faint astronomical phenomena.

CThe suspended mirrors used at LIGO are the most important components needed to measure gravitational waves.

DDetecting gravitational waves is difficult primarily because ground telescopes cannot see through cloud cover.

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