The correct answer is D. Ovary.
The corpus luteum is a temporary endocrine structure in the ovary that forms from an ovarian follicle after ovulation. It is responsible for the production of progesterone, which prepares the uterus for pregnancy. If pregnancy does not occur, the corpus luteum degenerates and is replaced by a corpus albicans.
The liver is a large, meaty organ that is located in the upper right abdomen. It is responsible for a variety of functions, including the production of bile, the metabolism of carbohydrates, proteins, and fats, and the detoxification of drugs and toxins.
The brain is the largest and most complex organ in the human body. It is responsible for controlling all voluntary and involuntary actions, as well as for processing information from the senses and generating thoughts and emotions.
The kidneys are a pair of bean-shaped organs that are located in the lower back. They are responsible for filtering waste products from the blood and producing urine.