Example of altruistic person and why

For example, parents and other family members often engage in acts of sacrifice in order to provide for the needs of family members. Reciprocal altruism: This type of altruism is based on a mutual give and take relationship. It involves helping another person now because they may one day be able to return the favor.

answer; /// i believe the correct answer is (when one group has an extremely high score at pretest;