**Core Concept**
Topical sulfonamides are a class of antimicrobials that are applied directly to the skin or mucous membranes to treat localized infections. They work by inhibiting the growth of bacteria through the disruption of folate synthesis.

**Why the Correct Answer is Right**
The correct answer is a topical sulfonamide, specifically silver sulfadiazine. It is commonly used to prevent and treat wound infections, particularly in burns. Silver sulfadiazine works by releasing silver ions, which have broad-spectrum antimicrobial activity, and sulfadiazine, which inhibits bacterial growth by interfering with folate synthesis. This combination is effective against a wide range of bacteria, including Pseudomonas aeruginosa.

**Why Each Wrong Option is Incorrect**
**Option A:** Sulfamethoxazole is an oral sulfonamide antibiotic, commonly used in combination with trimethoprim (co-trimoxazole) to treat various bacterial infections. It is not a topical agent.
**Option B:** Mafenide is a topical sulfonamide used to treat burns and wounds, but it is not as commonly used as silver sulfadiazine.
**Option C:** No information available for this option.

**Clinical Pearl / High-Yield Fact**
When treating burn wounds, it is essential to use a topical antimicrobial agent that is effective against Pseudomonas aeruginosa, a common pathogen in these cases. Silver sulfadiazine is a popular choice due to its broad-spectrum activity and ability to promote wound healing.

**Correct Answer:** B. Mafenide.