Final answer:
The gag reflex is mediated by the glossopharyngeal nerve (afferent) and the vagus nerve (efferent), where the glossopharyngeal nerve provides sensory input and the vagus nerve induces the motor response for the reflex.
Step-by-step explanation:
The gag reflex, also known as the pharyngeal reflex, is a function testing the integrity of certain cranial nerves. When we consider the innervation of the gag reflex, we look at two components: afferent and efferent pathways. The afferent (sensory) limb of the gag reflex is primarily provided by the glossopharyngeal nerve (cranial nerve IX), which conveys sensory information from the pharyngeal walls, while the efferent (motor) response is mediated by the vagus nerve (cranial nerve X), which controls the muscles responsible for the contraction of the pharynx during the reflex. Therefore, the correct option describing the innervation of the gag reflex is: Afferent: Glossopharyngeal, Efferent: Vagus. In addition, it's important to note that the facial nerve (cranial nerve VII) and the glossopharyngeal nerve are both involved in conveying gustatory stimulation and initiating salivation.