A. Your Choice
B. Green (Your Choice, but the other answers are only applicable if you use 1 color.)
C. Same color
D. The walls are 8 * 20 ft and 8 * 25 ft, and there are 2 of each of those.
That means you are painting 720 ft^2
There is 1 gallon per 400 ft^2, so you need 2 gallons of paint.
It costs $13.98 per gallon, so you need $13.98 * 2 = $27.96