I believe The answer is A.a class system
Karma is a concept of Hinduism which explains through a system where beneficial effects are derived from past beneficial actions and harmful effects from past harmful actions, creating a system of actions and reactions throughout a soul's (Atman's) reincarnated lives forming a cycle of rebirth.
It depends on exactly what you mean by multiple choice. How ever the definition is accompanied by several possible answers from which the candidate must try to choose the correct one.