Answer:
Vasopressin.
Step-by-step explanation:
Vasopressin hormone also known as anti-diuretic (ADH) hormone that regulates the tonocity of the body and maintains the fluid composition. This hormone is released from the posterior pituitary.
The vasopressin is a peptide hormone that plays an important role in the human beings. The promiscous males have multiple sexual partner and this decrease the amount of vasopressin in these males as compared with the monogamous males as vasopressin also regulates the sexual function in humans.
Thus, the answer is vasopressin.