Hint: Hormones are chemical messengers that are made up of either protein, amines, peptides, steroids, catecholamines, fatty acids, and glycoproteins. Hormones are the low molecular weight chemicals conducted by the blood. It is a hormone produced by the pituitary gland.
Complete answer: The secretion of the milk during sucking of the mammary glands by the baby is known as lactation. The first milk that is secreted by the mother is known as the colostrum.
a) Oxytocin – It is also known as Pitocin. Oxytocin is secreted by the posterior lobe of the pituitary gland or the Neurohypophysis. This hormone stimulates the vigorous contractions of the uterus at the time of childbirth. It also causes the release of the colostrum from the mammary gland by the sucking of the baby. Due to this reason, it is known as the milk ejection hormone and the birth hormone.
b) Relaxin – The relaxin hormone is secreted by the corpus luteum of the ovaries at the end of the pregnancy. This hormone causes the relaxation of the ligaments of the pelvic region and cervix during the process of childbirth.
c) Prolactin – It was earlier known as the Luteotropic hormone (LTH). It is secreted by the Adenohypophysis or the Anterior pituitary gland. This hormone regulates the growth of the mammary glands and the production of milk by them. It causes the release of the milk by the sucking of the baby after childbirth.
d) Progesterone – Progesterone hormone is secreted by the corpus luteum of the ovary. This hormone supports a pregnancy. Progesterone prepares the endometrium for implantation. It also acts on the mammary glands and stimulates the formation of the alveoli. Thus, based on the above information we can conclude that the Prolactin hormone stimulates the secretion of milk during the sucking of milk by the baby.
Hence, the correct answer is option C.
Note: The oxytocin hormone initiates the ejection of the milk for the first time when a baby sucks on the mammary glands. When the baby sucks the breasts, the hypophysis is stimulated to release oxytocin. The oxytocin-induced contractions help the mammary gland to release the stored milk. However, after this, the secretion of the milk is controlled by the prolactin hormone.