Summarizing her report on the need to belong,Rolanda states that

A) "Cooperation among our ancestors was uncommon."
B) "Social bonding is not in our nature; it is a learned human trait."
C) "Because bonding with others increased our ancestors' success at reproduction and survival,it became part of our biological nature."
D) "Our male ancestors were more likely to bond than were females."

Rolanda's report suggests that social bonding became a part of our biological nature because it increased our ancestors' success at reproduction and survival. This implies that social bonding is indeed a natural trait for humans. Option A is incorrect as cooperation among our ancestors was actually quite common. Option B is also incorrect as Rolanda's report does not suggest that social bonding is solely a learned trait. Option D is incorrect as Rolanda's report does not make any distinction between the bonding tendencies of male and female ancestors.