The correct option is D a hormone concerned with the maintenance of pregnancy.
Progesterone is produced by the ovary. It supports pregnancy. It also acts on the mammary glands and stimulates the formation of alveoli (sac-like structures that store milk) and milk secretion. It plays an important role in the thickening of the lining of the uterus every month in preparation for receiving and nourishing a fertilized egg every month.
Protein digesting enzymes are pepsin, trypsin etc.
The hormone oxytocin is synthesised by the hypothalamus and is released by the posterior pituitary. It initiates the contraction of the muscles of the uterus during childbirth.
Alkaptonuria occurs due to a defect in the HGD gene. This defect makes the body unable to properly break down the amino acids tyrosine and phenylalanine.