Refer to the Following Figure

Refer to the following figure:

Two firms, A and B, produce similar, but not identical, products. BRA and BRB are, respectively, the reaction functions for firms A and B, which compete primarily by price.
-A's best-response curve shows

A) all the Nash equilibrium prices that firm A can charge.
B) how firm B should react to any price set by A.
C) the price A should charge to maximize A's profits given each possible price that B might charge.
D) the price A should charge to maximize joint profits.
E) both c and d