The correct answer is D. human relations.
In the context of organizational culture, the study of human relations serves to identify problems arising from human interaction as well as possible ways to foster better interpersonal or intergroup dynamics.
Option a "human resrouces" refers to processes dealing with human capital in the context of labor agreements; option b "anthropology" talks about the study of human life from a social perspective; and option c "reinforcement" is a noun pointing to a complement for something which makes it stronger.
