Final answer:
The evolutionary driving forces behind eusociality are kin selection and inclusive fitness, which explain how complex social organizations, often involving sterile worker castes, evolve and contribute to the genetic success of relatives. Correct option is D.
Step-by-step explanation:
The evolutionary driving forces to preserve eusociality, a form of extreme sociality found in certain animals like bees, ants, and termites, include kin selection and inclusive fitness.
Eusociality involves complex social structures where members have specialized roles, and some may even forego their own reproduction to help relatives. Kin selection is a mechanism where organisms act to increase the reproductive success of their relatives, even at a cost to themselves. This ensures that the genes shared with their kin continue to be passed on.
Inclusive fitness is an extension of this idea, where an individual's genetic success is believed to be derived from cooperation and altruistic behavior, as it not only includes the individual's direct fitness (their personal reproductive success) but also the effects they have on the reproductive success of their relatives.
It broadens the focus from individual survival to the survival of the shared genes. In the context of eusocial animals, these concepts help explain why sterile worker castes evolve: though they do not reproduce, they help relatives with shared genes reproduce, which indirectly propagates their own genetic material.
Therefore, the correct answer to the student's question is D. both kin selection and inclusive fitness. These evolutionary principles, which emphasize the genetic success of relatives and cooperation within species, set the foundation for the persistence of eusocial behavior. Environmental adaptation also plays a role, but it is not the primary factor for the emergence and maintenance of eusociality.