Final answer:
The cranial nerves are the nerves that leave the brain directly and innervate structures in the head and neck.
Step-by-step explanation:
The correct answer is b. cranial nerves. Cranial nerves are the nerves that leave the brain directly. They emerge from the brainstem and innervate various structures in the head and neck. There are twelve pairs of cranial nerves, each with a specific function.