## **Core Concept**
Gynecomastia is the enlargement of breast tissue in males, often caused by an imbalance of sex hormones, specifically an increase in estrogen relative to testosterone. Certain drugs can disrupt this balance, leading to gynecomastia.

## **Why the Correct Answer is Right**
Spironolactone is a potassium-sparing diuretic that acts as an antagonist of the mineralocorticoid receptor. It also has anti-androgenic effects by blocking the androgen receptor, which can lead to an imbalance in sex hormones, favoring the effects of estrogen. This hormonal imbalance can cause gynecomastia.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option is blank and cannot be evaluated.
* **Option B:** This option is blank and cannot be evaluated.
* **Option D:** This option is blank and cannot be evaluated.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that drugs causing gynecomastia often do so by either increasing estrogen levels or decreasing androgen levels/effects. Spironolactone is a classic example of a drug that causes gynecomastia due to its anti-androgenic properties.

## **Correct Answer: C. Spironolactone**