Some species form social groups only with members of the same gender. For example, elephants form groups with only females and their offspring. Once the male offspring reach a certain age, they leave the group and become solitary. Which is a benefit of this type of social group structure?

Females do not have to compete for a mate.
Male offspring can belong to more than one social group.
Adult males can mate with females in several different social groups.
Females are the only ones responsible for taking care of the offspring.