By what mechanism does a second male mating with a female gain an advantage in sperm competition in some insects?

A) The second male's sperm physically dislodge the first male's sperm and insert themselves in place.
B) The accessory fluids from the second male's semen is able to displace stored sperm from competing males.
C) The second male will have larger testes and so produce larger numbers of sperm.
D) Answers A and B are both correct.