Final answer:
The deep temporal and masseteric nerves are responsible for motor functions and are therefore classified as motor fibers.
Step-by-step explanation:
The deep temporal and masseteric nerves, which originate from the mandibular branch of the trigeminal nerve (V3), are responsible for motor functions. These nerves innervate the temporalis and masseter muscles, respectively, which are muscles of mastication involved in chewing. Thus, they both carry motor fibers. Other branches of the trigeminal nerve carry different types of fibers, but in this case, options such as sensory, autonomic, or mixed do not apply to the deep temporal and masseteric nerves.