What is the function of the arrector pili muscle?

The arrector pili muscle plays a key role in the body's response to cold or emotional stimuli by causing the hair follicles to become erect, leading to the phenomenon known as goosebumps. When these muscles contract, they pull on the hair follicle, causing the hair to stand up. This response can create an insulating layer of air close to the skin, which is beneficial in cold environments. Additionally, the contraction of the arrector pili can also serve as a physiological response during situations like fear or excitement, often referred to as the fight-or-flight response. This involuntary reaction illustrates the muscle's function beyond just maintaining body temperature; it also ties into our emotional responses. Thus, the correct answer highlights the primary role of the arrector pili muscle in creating goosebumps.