Which of the Following Does the Textbook Mention as Supporting

Which of the following does the textbook mention as supporting the concept of reciprocal altruism?

A) Human mothers can recognize their new babies from photographs, even when they have had little contact with the baby.
B) Across cultures, people are more willing to help closely related individuals than strangers.
C) Chimpanzees will share food with other primates who share with them.
D) Identical twins cooperate more when working together compared to fraternal twins.