Answer: option C) enables the "let-down" reflex to occur when a woman breastfeeds her baby. 
Step-by-step explanation:
Oxytocin is a hormone secreted by the posterior pituitary gland. It stimulates the contractions of smooth muscles such as 
- uterus facilitating childbirth 
- ducts of the mammary glands resulting in ejection of milk. Thus, it is also called as milk-let-down-ejection factor. 
So, option C is the correct answer