**Core Concept**
Androgen receptor blockers are a class of medications that inhibit the action of androgens (male hormones) by blocking their receptors. This class of drugs is used in the treatment of conditions such as prostate cancer, hirsutism, and androgenetic alopecia.

**Why the Correct Answer is Right**
Finasteride, a 5-alpha-reductase inhibitor, is not the correct answer as it primarily inhibits the conversion of testosterone to dihydrotestosterone (DHT) rather than blocking androgen receptors directly. Similarly, spironolactone is a potassium-sparing diuretic that also has anti-androgen effects, but it is not a specific androgen receptor blocker. Flutamide is a nonsteroidal anti-androgen that directly blocks the androgen receptor, making it the correct choice.

**Why Each Wrong Option is Incorrect**
**Option A:** Finasteride is incorrect because it primarily inhibits the conversion of testosterone to DHT, rather than directly blocking androgen receptors.
**Option B:** Spironolactone is incorrect because it is a potassium-sparing diuretic with anti-androgen effects, but it is not a specific androgen receptor blocker.
**Option C:** None provided, skipping to next option.

**Clinical Pearl / High-Yield Fact**
Androgen receptor blockers like flutamide are used in the treatment of prostate cancer and can cause gynecomastia as a side effect due to the imbalance of hormones.

**Correct Answer: C. Flutamide**