Mixed cranial nerves containing both motor and sensory fibers include all except which of the following?

a. facial
b. oculomotor
c. trigeminal
d. olfactory

The correct answer will be option-D

Explanation:

Cranial nerves are the twelve type of nerves of the peripheral nervous system which innervate or supply to the structures of the neck and head.  Mixed cranial nerves are a type of cranial nerves which contain mixtures of both sensory and motor fibers or nerves.  

The main nerves of the mixed cranial nerves are the facial nerve,  glossopharyngeal nerves, trigeminal nerves (control mastication muscles) and the oculomotor (control eye movement).  The olfactory nerves transmit the sense of smell to the nasal cavity and are not considered the part of the mixed cranial nerves.

Thus, option-D is the correct answer.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).