## **Core Concept**
The World Health Organization (WHO) provides criteria for normal semen analysis parameters. Sperm count, or sperm concentration, is a critical component of male fertility assessment.

## **Why the Correct Answer is Right**
The WHO criteria for a normal sperm count is ≥15 million sperm per milliliter (mL) of ejaculate. This parameter is crucial in assessing male fertility, as low sperm count (oligozoospermia) can be a cause of infertility. The correct answer reflects this threshold.

## **Why Each Wrong Option is Incorrect**
* **Option A:** 5 million/mL is below the threshold for normal sperm count according to WHO criteria, indicating oligozoospermia.
* **Option B:** 10 million/mL, although closer, still falls short of the WHO's minimum threshold for a normal sperm count.
* **Option D:** 20 million/mL, while within the normal range, is not the minimum threshold.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that a normal sperm count does not guarantee fertility, as other factors like motility and morphology also play critical roles. According to WHO, for a semen sample to be considered normal, it should have: a concentration of ≥15 million sperm/mL, ≥40% with progressive motility, and ≥4% with normal morphology.

## **Correct Answer:** . 15 million/mL