SAT OwlQuestion bank / Text Structure and Purpose
Some astronomers have explained the unusually tilted orbits of certain distant objects in the outer solar system by proposing an undiscovered ninth planet whose gravity pulled them out of line. Astrophysicist Tomasz Brecht offers a different account. In computer simulations, he found that the combined gravity of many small icy bodies, each too faint to detect, could produce the same tilts without any large planet. Brecht acknowledges that his model does not rule out a ninth planet, but he notes that it requires fewer untested assumptions about the solar system's history.
Which choice best describes the overall structure of the text?
It presents a widely accepted explanation and then reports evidence that definitively disproves it.
It explains how a planet was discovered and then describes objections to that discovery.
It presents one explanation for a phenomenon and then outlines an alternative explanation, noting both a limitation and an advantage of the alternative.
It compares two computer simulations and concludes that both support the same explanation.
Show answer and explanation
Answer: C
The text first gives the ninth-planet explanation for tilted orbits, then introduces Brecht's alternative based on many small bodies. It ends by noting that his model does not rule out a ninth planet (a limitation) but requires fewer assumptions (an advantage). Choice C describes this sequence.
Choice A is tempting, but Brecht explicitly says his model does not rule out a ninth planet, so nothing is "definitively" disproved.
Got it wrong? On SAT Owl, Owl looks at the answer you chose and explains the exact mistake, then gives you similar questions until it sticks. Get your predicted SAT score free.