Juvenile monkeys that are separated from their mothers will often show self-destructive behavior, such as picking at their fur or refusing to eat. These behaviors are the most prevalent in monkeys that are caged alone, are somewhat less prevalent when the monkeys are caged with other, unrelated juveniles and adult males, and are the least prevalent, but still observable, when the monkeys are caged with a mixed-gender group of unrelated, adult monkeys.

Which of the following hypotheses best explains the phenomenon described above?

A: The presence of unrelated juvenile and adult male monkeys causes more self-destructive behavior in juvenile monkeys than does the presence of a mixed-gender group of unrelated adult monkeys.
B: The presence of unrelated adult female monkeys is more important to juvenile monkeys in alleviating distress caused by being separated from their mothers than is the presence of unrelated juvenile monkeys.
C: The presence of unrelated adult male monkeys is threatening to juvenile monkeys, causing self-destructive behavior similar to that caused by the separation of juvenile monkeys from their mothers.
D: The presence of unrelated adult female monkeys serves as a suitable substitute for a juvenile monkey's mother following a separation from the mother.
F: Juvenile monkeys that display self-destructive behavior will engage in this behavior the least when reunited with their mothers, and will engage in this behavior slightly more when caged with adult female monkeys who are not their mothers.

OA is B