Final answer:
The distribution of motor nerve fibers to the arrector pili muscles attached to hair follicles allows for the production of goosebumps.
Step-by-step explanation:
Motor nerve fibers are distributed to the arrector pili muscles attached to the hair follicles, which allows for the production of goosebumps. The arrector pili muscles contract in response to stimuli from the sympathetic nervous system, especially when the body is cold or experiencing strong emotions. This muscle contraction causes the hair follicles to move, making the hair shafts stand up and resulting in goosebumps. This reaction is part of the body's way of trapping more air under the hairs to provide an additional layer of insulation.