Answer:
D
Step-by-step explanation:
This is called "implication". So if A (is true), then B MUST be true. If B is false, the implication is false. In all other cases, the implication is true. Suppose A is false, then it doesn't matter what B is, the implication is true, since we don't care what B is.
It's a bit confusing I suppose. Below is a truth table using P and Q in stead of A and B.