Progesterone is a hormone secreted by the:

Progesterone is primarily secreted by the ovaries, particularly after ovulation during the luteal phase of the menstrual cycle. This hormone plays a crucial role in regulating various reproductive processes, including preparing the uterine lining for potential implantation of a fertilized egg. It also helps maintain pregnancy by supporting the uterine environment until the placenta can take over this function.

Understanding the role of the ovaries in hormone production is essential, as they produce not only progesterone but also estrogen, which is important for female reproductive health. While the other glands mentioned, such as the pineal gland, testes, and pituitary gland, produce important hormones of their own, they are not the primary sources of progesterone in the female body. Thus, the ovaries are the correct answer when identifying the site of progesterone secretion.