4

Set 3: Central Ideas

Explanation

Answer: D

PASSAGE

The following text describes the planet Mars. Mars is often called the "Red Planet" because of the iron oxide prevalent on its surface, which gives it a reddish appearance. Although it is currently a cold desert world, scientists have found evidence of ancient river valleys and lake beds. This suggests that billions of years ago, Mars may have had a thicker atmosphere and liquid water, potentially supporting life.

What does the text suggest about the history of Mars?

A. It has always been a dry, cold desert
B. It may have once been wetter and warmer
C. It is currently inhabited by microscopic life
D. It was once closer to the sun than Earth✓ Correct

Detailed Explanation

Choice B is correct. The text mentions 'evidence of ancient river valleys' and suggests Mars may have had a 'thicker atmosphere and liquid water,' implying a warmer, wetter past.

Key Evidence:

• "evidence of ancient river valleys"

• "may have had... liquid water"

Why others are wrong: A (Opposite (evidence of water implies it wasn't always dry)), C (Not mentioned (says 'potentially supporting', not currently)), D (Not mentioned).

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