Final answer:
The lack of smell involves the olfactory nerve and is called anosmia. This condition can result from blunt force trauma or aging, affecting the neural regeneration process.
Step-by-step explanation:
The correct answer to the question regarding the lack of smell is D) Olfactory; anosmia. Anosmia is the loss of the sense of smell, and it generally occurs due to damage to the olfactory nerve, which is the first cranial nerve responsible for the sense of smell. Anosmia can arise from different causes, such as blunt force trauma to the head, which can sever the olfactory nerve, or through aging, where the renewal of sensory neurons in the olfactory epithelium declines, preventing new axons from extending into the CNS along existing fibers of the olfactory nerve.