**Core Concept**
Anti-Müllerian hormone (AMH) is a protein hormone produced by the granulosa cells of small antral follicles in the ovaries. It is a marker of ovarian reserve, reflecting the number of remaining follicles in the ovaries.

**Why the Correct Answer is Right**
In low ovarian reserve, the number of remaining follicles is reduced, leading to decreased production of AMH. This is because AMH is produced by the granulosa cells of small antral follicles, and with fewer follicles, there is less AMH production. As a result, AMH levels are lower in women with low ovarian reserve, making it a useful marker for assessing ovarian reserve and predicting fertility potential.

**Why Each Wrong Option is Incorrect**
* **Option A:** Not relevant to the concept of low ovarian reserve and AMH levels.
* **Option B:** Actually, AMH levels are low in women with low ovarian reserve, not high.
* **Option D:** While AMH is a marker of ovarian reserve, it is not directly related to the number of follicles that have ovulated, but rather to the number of remaining follicles.

**Clinical Pearl / High-Yield Fact**
Remember that AMH is a marker of ovarian reserve, and low AMH levels are associated with reduced fertility potential. This is an important consideration for women undergoing fertility treatments or evaluating their reproductive options.

**Correct Answer: B. Low.**