The Mariner 9 mission captured close-up photographs of Mars that revealed a network of valleys that resembled stream beds on Earth. These photos also suggested that Mars formerly had a thick enough atmosphere to trap the sun's heat. If this is correct, something happened on Mars billions of years ago that caused the planet's atmosphere to be stripped away. This paragraph provides the strongest evidence for the claim that
A. Mars today has a thin atmosphere, if any at all.
B. Mars used to have a thicker atmosphere than the Earth.
C. The first photographs of Mars were taken by the Mariner 9 spacecraft.
D. Mars is nearer to the sun than the Earth.
Answer:A
The Mariner 9 mission captured close-up photographs of Mars that revealed a network of valleys that resembled stream beds on Earth. These photos also suggested that Mars formerly had a thick enough atmosphere to trap the sun's heat. If this is correct, something happened on Mars billions of years ago that caused the planet's atmosphere to be stripped away. This paragraph provides the strongest evidence for the claim that
A. Mars today has a thin atmosphere, if any at all. B. Mars used to have a thicker atmosphere than the Earth. C. The first photographs of Mars were taken by the Mariner 9 spacecraft. D. Mars is nearer to the sun than the Earth.
Explanation: According to the passage, Mars originally had a dense atmosphere that was stripped away. The text does not contain any other options, true or false.