In which situation might the pilomotor reflex be triggered?

The pilomotor reflex, also known as piloerection, is primarily triggered in response to cold temperatures. When the body is exposed to cold, the sympathetic nervous system activates, causing tiny muscles at the base of hair follicles to contract, resulting in the hair standing upright. This reaction serves to create a layer of insulation and trap heat close to the skin, helping to maintain body temperature.

While other situations may involve various physiological responses, such as exercise inducing sweating or emotions altering heart rate, these do not typically elicit the specific reaction associated with the pilomotor reflex. In summary, the correct answer pertains to the body’s natural defensive mechanisms against cold, which is an important aspect of thermoregulation.