A Principal Theory in Social Psychology Is Social Exchange Theory

A principal theory in social psychology is social exchange theory (Homans,1961; Thibaut & Kelley,1959) .According to this theory,we will be most likely to help others

A) for whom we feel empathy.
B) who have already helped us.
C) who are closely related to us.
D) when the benefits outweigh the costs.
E) who are similar to us.