**Core Concept**
The question requires knowledge of antifungal medications that have a broad spectrum of activity, targeting both dermatophytes (a type of fungus that causes skin infections) and Candida species (a type of fungus that causes yeast infections).

**Why the Correct Answer is Right**
Terbinafine is a synthetic allylamine antifungal agent that inhibits squalene epoxidase, an enzyme essential for the conversion of squalene to lanosterol in the fungal cell membrane. This action disrupts the cell membrane, ultimately leading to fungal cell death. Terbinafine is effective against a wide range of dermatophytes and has excellent penetration into the skin and nails, making it an ideal treatment for both superficial and deep fungal infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Griseofulvin is an antifungal medication that targets microtubule function in fungal cells, but it is primarily used to treat dermatophyte infections and is not effective against Candida species.

**Option B:** Fluconazole is an azole antifungal that inhibits lanosterol 14α-demethylase, an enzyme involved in ergosterol synthesis. While fluconazole is effective against many Candida species, it is not typically used to treat dermatophyte infections.

**Option C:** Ketoconazole is an imidazole antifungal that has a broad spectrum of activity, including both dermatophytes and Candida species. However, its use is limited due to potential liver toxicity and is generally not considered a first-line treatment for either type of infection.

**Clinical Pearl / High-Yield Fact**
Terbinafine has a high affinity for keratin, which allows it to accumulate in skin and nail tissues, making it an effective treatment for fungal infections in these areas.

**Correct Answer: C. Ketoconazole**