**Core Concept**
The luteal phase is the latter phase of the menstrual cycle, characterized by the formation of the corpus luteum, which secretes **progesterone**. This hormone plays a crucial role in preparing the uterus for a potential pregnancy. The peak level of plasma **progesterone** is an important indicator of luteal function.

**Why the Correct Answer is Right**
The correct answer is related to the timing and levels of **progesterone** secretion during the luteal phase. Normally, **progesterone** levels surge after ovulation, peaking around the mid-luteal phase, approximately 7-10 days after ovulation. This peak is essential for maintaining the endometrium in a state receptive to implantation of a fertilized egg.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not accurately reflect the timing of peak **progesterone** levels.
**Option B:** Incorrect as it suggests an earlier peak than what is typically observed.
**Option C:** Incorrect because it implies a later peak than what is expected in a normal luteal phase.
**Option D:** Incorrect as it does not specify the correct timing of the peak **progesterone** level.

**Clinical Pearl / High-Yield Fact**
Remember, peak **progesterone** levels are crucial for endometrial preparation and implantation. Any disruption in this process can lead to issues with fertility or early pregnancy loss.

**Correct Answer:** D. 7-10 days after ovulation, around 20-24 days of a 28-day menstrual cycle, plasma progesterone levels peak.