The correct option is B Oxytocin
Prolactin is a hormone produced by the anterior lobe of the pituitary gland and is responsible for the synthesis and secretion of milk.
Oxytocin is a hormone produced by the hypothalamus. But it is stored and released by the posterior lobe of the pituitary gland. It is responsible for the ejection of milk.
Estrogen is a hormone produced by the developing follicles of the ovary. It is responsible for the deposition of fat in the mammary glands.
So, the hormones responsible for milk ejection is- oxytocin.