Final answer:
(A) Head
The superior cervical ganglion, which is part of the sympathetic nervous system, sends postganglionic sympathetic fibers around the carotid arteries, projecting to the head.
Step-by-step explanation:
The superior cervical ganglion is one of the paravertebral ganglia of the sympathetic nervous system that projects to the head. The branches of the superior cervical sympathetic ganglion wrap around the carotid arteries to distribute sympathetic fibers to the head.
When addressing the function of these sympathetic fibers, they are specifically involved as postganglionic sympathetic fibers. Thus, the branches of the superior cervical sympathetic ganglion end around carotids for sympathetics to the head, making the correct answer 'a. head.'