Final answer:
Sympathetic preganglionic fibers are short, whereas postganglionic fibers are long. This is due to the proximity of the sympathetic ganglia to the central nervous system and the greater distance postganglionic fibers have to travel to reach the target organs.
Step-by-step explanation:
In general, sympathetic preganglionic fibers are short, and postganglionic fibers are long. This means that for the sympathetic nervous system, the axons from the central neuron (preganglionic fibers) that project to a sympathetic ganglion are relatively short and are myelinated. Conversely, the axons from a ganglionic neuron (postganglionic fibers) that project to the target effector are long and are typically unmyelinated, because they have to reach further to the target organs or effectors.
The correct response to the question about the lengths of sympathetic preganglionic and postganglionic fibers is 'c. short; long'.