Okay, so what is the primary function of the dartos muscle? Remember, the dartos muscle is a sheet of smooth muscle inside the scrotum, and when the temperature outside gets cold, that muscle will contract. This action will kind of wrinkle the scrotum and pull the testes closer together, which will decrease their surface area and allow them to conserve heat. So, our answer is going to be a) the temperature regulation of the testes.
So, just looking quickly at options b and c, the contraction of the vas deferens and to eject sperm from the testes—both of these actions happen through smooth muscle contractions of the vas deferens itself. So, the dartos muscle is not really helping with that at all. Then, option c can be a little bit tricky. It says the relaxation of the scrotum, and the dartos muscle, of course, can relax just like any other muscle. However, its main function is not to relax. Its function is to help regulate the temperature within the scrotum, so our answer here is going to be a.
