Our teacher asked us to read an article. Here is a part of it:
Some scientists believe there are billions of planets in the universe. A few of them might have conditions for life. Mars is a good example. It has ice and a thin atmosphere. In the past, it might have had water. So, maybe tiny living things existed there.
According to the text, why is Mars a good example for life in the past?
A)Because it has a thick atmosphere.
B)Because it might have had water.
C)Because it is close to Earth.
D)Because it is billions of years old.