Option d is the correct answer. Mimamsa is a school of Indian philosophy that is related to the doctrine of Apurva. Apurva is a concept that explains the connection between the performance of a Vedic ritual and its result. According to Mimamsa, the result of a ritual is not immediate or visible, but delayed and invisible. Apurva is the unseen force or potency that is generated by the ritual, and that ensures that the performer will receive the desired result in the future. Apurva is also the basis of moral causation, as it links one's actions with their consequences. Mimamsa believes that by following the Vedic commands and performing the prescribed rituals, one can attain happiness and liberation.