What Is/are the Stimulus(-I)for Contraction of the Arrector Pili Muscles

Question

What is/are the stimulus(-i)for contraction of the arrector pili muscles?
A)Low blood pH
B)Dry skin
C)Cold temperature or fear
D)Hot temperature
E)Hot temperature or fear

Accepted Answer

The contraction of the arrector pili muscles is stimulated by cold temperature or fear, causing the hairs on the body to stand up straight and trap a layer of air to provide insulation. Dry skin, low blood pH, and hot temperature or fear do not directly stimulate the contraction of the arrector pili muscles.