Sexual dimorphism:

a. tends to be lower than in groups where males disperse and compete with unrelated males.

b. determines male and female social hierarchy.

c. is the study of sexual intercourse between primates.

d. relates to sexual courtship rituals in primates.

The answer is a. tends to be lower than in groups where males disperse and compete with unrelated males.

Sexual dimorphism refers the difference size of sexual organ between two or more organism. For human in general, the males tend to be more conscious about the size of the sexual organ compared to the females, which lead to unnecessary insecurity and depression.

Sexual dimorphism tends to be lower than in groups where males disperse and compete with unrelated males. Often this has to do with direct completion. Those on regular direct contact have more social opportunities to attract a mate and displays are less necessary.