The correct answer is option 'D' - the anterior lobe of the pituitary gland.

The pituitary gland is a small pea-sized gland located at the base of the brain. It is often referred to as the "master gland" because it secretes several hormones that regulate various functions in the body. These hormones are classified into two main categories: anterior pituitary hormones and posterior pituitary hormones.

The anterior lobe of the pituitary gland is responsible for producing and releasing several important hormones, including the follicle-stimulating hormone (FSH). FSH is a gonadotropin hormone that plays a vital role in the reproductive system, particularly in the regulation of the menstrual cycle and the production of eggs in females and sperm in males.

Here's a breakdown of the process:

1. Hypothalamus: The hypothalamus, a region of the brain, releases gonadotropin-releasing hormone (GnRH), which stimulates the anterior pituitary gland.

2. Anterior Pituitary Gland: Upon receiving the signal from GnRH, the anterior pituitary gland secretes follicle-stimulating hormone (FSH) into the bloodstream.

3. Target Organs: FSH primarily acts on the reproductive organs, including the ovaries in females and the testes in males.

4. Females: In females, FSH stimulates the growth and development of ovarian follicles, which contain the eggs. FSH also promotes the secretion of estrogen by the ovarian follicles.

5. Males: In males, FSH stimulates the production of sperm cells within the seminiferous tubules of the testes.

6. Feedback Mechanism: As the ovarian follicles mature and the estrogen levels increase in females, they exert negative feedback on the hypothalamus and the anterior pituitary gland, inhibiting the further secretion of FSH.

In summary, the follicle-stimulating hormone (FSH) is secreted by the anterior lobe of the pituitary gland. It plays a crucial role in the regulation of the reproductive system and is involved in the maturation of eggs in females and the production of sperm in males.