Which of these were observed from Earth, prior to spacecraft missions to Mars?
A) seasonal changes in the polar caps
B) eruptions of Mount Olympus
C) dust storms capable of covering the entire planet
D) Both A and C are correct.
E) All of the above are correct.
Question 2
For every star with a mass greater than 10 solar masses, about how many stars are there with masses less than a solar mass?
A) 1
B) 3
C) 10
D) 30
E) 200