Scientists are looking for signs that Mars could have been habitable in the past. Think of the things that a planet needs to be habitable. With these things in mind, what signs of habitability would you look for on Mars?

What evidence suggests that life might have been possible on Mars in the distant past?

Although the surface of Mars is inhospitable today, there is clear evidence that in the distant past, the Martian climate allowed liquid water – an essential ingredient for life as we know it – to pool at the surface.

Explanation:

the answer would be b).