In the 1960's . long-term studies of primate behavior often

In the 1960's . long-term studies of primate behavior often used
as subjects tamarins, small monkeys that were thought ideal because
they require only small cages, bread frequently, and grow quickly.
Field studies were not used because they were costly and difficult.
Tamarins were kept caged in male-female pairs, because otherwise,
serious fights erupted between unrelated females. On the basis of the
fact that breeding occurred, tamatins were viewed as monogamous.

The view taken by the researchers concerning the monogamy of tamarins
depended on a questionable assumption.Which of the following could
have served as that assumption?

(A) The suppression of fighting between related females serves to
protect their common genetic inheritance.
(B) Adult male tamatins contribute to the care of tamarin infants.
(C) The social system of tamarins requires monogamous pairing.
(D) Male tamarin monkeys do not display aggressive behavior in the
wild.
(E) The way the tamarins were kept in cages did not affect their
mating behavior.