This is a reading question. You have to know what all the terms mean.
B: is the first one you have to think about. All real solutions. Is that the answer, or do you have to think about it more. The key word is solutions. So that takes in A. So B is the answer.
A is the second best answer. Any solution has to be on the blue line. The blue line is the visual record of what works in B. Well, why not pick A? It is because B is more general, and it includes A.
C More than whole numbers solve this question. The line is continuous.
D There are negative solutions as well. Not the answer.
