The correct answer is Cremaster muscle.
In human males, the cremaster muscle refers to a thin covering of smooth and striated muscle located in the scrotum and inguinal canal between the internal and external layers of spermatic fascia, enveloping the spermatic cord and testis.
The cremaster muscle elevates and lowers the testis in order to monitor its temperature. When a man comes into the surrounding of colder temperature, the muscle makes the testis to move against the body. The more the testis comes closer to the body, the less it comes in contact with the cold air.
