C) If you were to hit it you would knock the boat's brains out
The flower dances in the rain
The answer is B. Your Welcome. Comment if it is wrong.
"Research suggests that Mars has some features that would support life, but most conditions are too harsh for it." is <span>definitely</span> a main idea as for the second one your best bet is to talk about possible life on mars in the future so that 4th sentence is going to be your friend.
I could try but you have to start writing it on your own first so I can just add on ideas and share my opinions.