**Core Concept**
The antimullerian hormone (AMH) is a protein hormone that plays a crucial role in the regulation of ovarian function and follicular development. It is a member of the transforming growth factor beta (TGF-β) superfamily and is produced by the granulosa cells of the ovaries.

**Why the Correct Answer is Right**
AMH is secreted by the granulosa cells of the small antral follicles in the ovaries, particularly those in the early stages of development. It acts as a negative feedback mechanism to suppress the growth of follicles, thereby regulating the number of follicles that reach ovulation. AMH also inhibits the production of FSH (follicle-stimulating hormone) by the pituitary gland, which further regulates follicular development.

**Why Each Wrong Option is Incorrect**
* **Option A:** The corpus luteum is not responsible for secreting AMH, as it produces progesterone and inhibin instead.
* **Option B:** The testes produce Müllerian-inhibiting substance (MIS), also known as anti-Müllerian hormone (AMH), which is different from the AMH produced by the ovaries.
* **Option D:** The pituitary gland secretes FSH and LH, but not AMH, which is produced by the ovarian granulosa cells.

**Clinical Pearl / High-Yield Fact**
AMH levels are a useful marker for ovarian reserve, with lower levels indicating reduced ovarian function and potential premature ovarian failure.

**Correct Answer: B. The testes.**