Mock Q on Econ w/ Twisted answer understand, question, because, product, returns

wilslm

In the SR, the Average Product of labor:
a) is increasing when the total product of labor is increasin
b) is at maximum where it intersects the Marginal product of labor
c) is upward-sloping if the firm is eperiencing diminishing marginal returns to labor
So the answer is B. However, the issue i have with this question is that it could also be A, because the Average Product of labor is also 1st increasing and then decreasing as diminishing marginal returns take effect.
I dont understand why they threw 2 legit answers in there. Anyone got some clarification on this?