In the Figure Below, the Lighter Gray Circles Represent Single-Male

Multiple Choice

In the figure below, the lighter gray circles represent single-male breeding systems in primates and the darker gray circles indicate multi-male systems. Which of the following statements is consistent with these data?

A) Single-male breeding systems select for smaller testes size because sperm are not needed to increase reproductive success.
B) Body weight does not influence testes size because selection only favors large testes in multi-male systems.
C) Species with multi-male systems evolve larger testes because they have higher body weights.
D) Selection favors large testes relative to body weight when a male's sperm must compete directly with other males.