Final answer:
The correct answer is 'B. indirect fitness', which refers to the reproductive success achieved through the propagation of genetic material by relatives, a concept closely related to inclusive fitness and kin selection.
Step-by-step explanation:
The student is asking about a concept in biology that involves the effects of an organism's behavior on the reproductive success of its relatives. The correct answer to the question is B. indirect fitness, often referred to as inclusive fitness.
Inclusive fitness takes into account not only the reproductive success that an individual achieves through its own offspring (direct fitness), but also the success achieved by helping relatives (who share common genes) to reproduce. This is encapsulated in the concept of kin selection, where organisms may act in a way that is seemingly altruistic, by helping close kin, thus increasing their indirect fitness by ensuring the propagation of shared genetic material.