Altruistic Behavior Benefits Others While Being a Disadvantage to the Altruistic

Altruistic behavior benefits others while being a disadvantage to the altruistic individual.What observation might best explain this behavior?

A) Helping behavior directed toward related individuals is costly and has probably never evolved;most altruistic behavior is random.
B) Altruistic behavior is most common in groups with a low degree of genetic relatedness.
C) Altruistic behavior is widespread in primates,but as observed by Wrangham,is absent in chimpanzees.
D) Altruistic behavior is often directed toward related individuals and enhances inclusive fitness.