**Core Concept**
Ovulation is a critical phase in the menstrual cycle where the mature ovum is released from the ovarian follicle, making it available for fertilization. This process is tightly regulated by a complex interplay of hormonal and neural signals.

**Why the Correct Answer is Right**
Ovulation is triggered by a surge in luteinizing hormone (LH) from the anterior pituitary gland, which is released in response to a decrease in estrogen levels. This LH surge causes the mature ovum to be released from the antral follicle, leading to ovulation. The timing of ovulation is precisely coordinated with the menstrual cycle, typically occurring around day 14 of a 28-day menstrual cycle.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ovulation is not triggered by follicle-stimulating hormone (FSH) alone. While FSH plays a crucial role in follicular development, it is the LH surge that ultimately leads to ovulation.
**Option B:** This option is incorrect because ovulation does not coincide with the peak levels of estrogen. In fact, estrogen levels decrease slightly before ovulation, triggering the LH surge.
**Option C:** This option is incorrect because ovulation is not directly related to the timing of menstruation. Menstruation occurs when there is no pregnancy, and ovulation is a separate process that occurs mid-cycle.

**Clinical Pearl / High-Yield Fact**
A mnemonic to remember the sequence of hormonal changes during the menstrual cycle is "FSH → Estrogen → LH → Ovulation". This sequence highlights the critical role of LH in triggering ovulation.

**Correct Answer: D.**