**Core Concept**
The question is testing the student's knowledge of the typical size of ovarian follicles at different stages of development. In the menstrual cycle, follicles undergo various stages of growth and maturation, releasing an egg (ovulation) when they reach a certain size.

**Why the Correct Answer is Right**
Follicles of a diameter of 5 mm are typically seen during the follicular phase of the menstrual cycle, when several follicles start to grow and mature in response to follicle-stimulating hormone (FSH) from the pituitary gland. As the dominant follicle grows, it reaches a size of about 5-6 mm in diameter, while the smaller follicles undergo atresia. The growth of the follicle is an important process that prepares the egg for ovulation.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot comment on it.
* **Option B:** This option is not provided, so we cannot comment on it.
* **Option C:** This option is not provided, so we cannot comment on it.
* **Option D:** This option is not provided, so we cannot comment on it.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the growth of follicles is a dynamic process, and the size of follicles can vary depending on individual factors, such as hormonal imbalances or polycystic ovary syndrome (PCOS). A follicle size of 5 mm is a general guideline and may not always be accurate in clinical practice.

**Correct Answer:** A.