**Core Concept**
Clofazimine is an antimicrobial agent used in the treatment of leprosy, a chronic bacterial infection caused by Mycobacterium leprae. This drug has a unique side effect profile, which includes the development of ichthyosis, a skin condition characterized by dry, scaly, and thickened skin.

**Why the Correct Answer is Right**
Clofazimine causes ichthyosis due to its lipophilic nature, which leads to the accumulation of the drug in the skin. This accumulation causes a range of dermatological side effects, including dry skin, hyperpigmentation, and ichthyosis. The exact mechanism is not fully understood, but it is thought to be related to the drug's ability to bind to melanin and other skin components.

**Why Each Wrong Option is Incorrect**
**Option A:** Dapsone is another antimicrobial agent used in the treatment of leprosy, but it is not associated with ichthyosis. Dapsone is known for its hematological side effects, including hemolysis and methemoglobinemia.

**Option C:** Rifampicin is an antibacterial agent used in the treatment of tuberculosis, not leprosy. While rifampicin has a range of side effects, ichthyosis is not typically associated with this drug.

**Option D:** Clarithromycin is an antibiotic used to treat a range of bacterial infections, including those caused by Mycobacterium leprae. However, ichthyosis is not a known side effect of clarithromycin.

**Clinical Pearl / High-Yield Fact**
When treating patients with leprosy or other skin conditions, it is essential to monitor for signs of skin toxicity, including dry skin, hyperpigmentation, and ichthyosis. Clofazimine is a key contributor to these side effects, and patients should be closely monitored for these symptoms.

**✓ Correct Answer: B. Clofazimine**