Which gland is known as the female sex gland?

The ovary is known as the female sex gland because it is responsible for producing eggs (ova) and hormones such as estrogen and progesterone, which play crucial roles in regulating the female reproductive system and menstrual cycle. The ovaries not only release eggs for potential fertilization but also contribute to the development of secondary sexual characteristics and the maintenance of pregnancy.

Understanding the function of the ovaries is vital in recognizing their roles in women's health, fertility, and overall hormonal function, making them a key component of the female reproductive system. The other options listed serve different functions: the uterus is where a fertilized egg implants and develops during pregnancy, the fallopian tubes are the pathways for the eggs to travel from the ovaries to the uterus, and the vagina is the canal through which birth occurs and also serves as a passage for menstrual fluid.