There Are a Number of Species of Mammals Where the Males

There are a number of species of mammals where the males often mount other males.The most accurate explanation of this behaviour is that

A) there is a relatively large amount of actual homosexual behaviour among most species of mammals
B) this behaviour is a reflection of the dominance hierarchy in the respective group
C) this behaviour is a consequence of a scarcity of females in the group
D) it shows bisexual impulses in primates