For water to have been stable on Mars in the past,
A) temperature must have been higher and the atmospheric pressure lower
B) temperature must have been lower and the atmospheric pressure higher
C) both the temperature and the atmospheric pressure must have been higher
D) both the temperature and the atmospheric pressure must have been lower
Question 2
Most of the deuterium that formed right after the Big Bang
A) is still around today.
B) broke down into electrons and neutrons.
C) turned into dark matter.
D) quickly burned into helium nuclei.
E) was found in the globular clusters.