Which of the following is a main female reproductive organ?

The uterus is a vital female reproductive organ with several important functions in human reproduction. It is the structure in which a fertilized egg implants and develops during pregnancy. The lining of the uterus, called the endometrium, thickens in preparation for the potential implantation of a fertilized egg and plays a key role in supporting the developing fetus throughout pregnancy. Additionally, during menstruation, the endometrium breaks down and sheds if pregnancy does not occur.

In contrast, the prostate gland and testes are structures found in the male reproductive system; the prostate gland produces seminal fluid, while the testes are responsible for sperm production. The penis is also part of the male reproductive anatomy and serves to deliver sperm during sexual intercourse. Therefore, the uterus is distinctly identified as a main organ within the female reproductive system, highlighting its essential role in reproduction.