**Core Concept**
Trichophyton, Microsporum, and Epidermophyton are common genera of fungi that cause dermatophytosis, a superficial fungal infection of the skin, hair, or nails. These fungi are known to infect hair, skin, and nails, leading to various clinical manifestations.

**Why the Correct Answer is Right**
Epidermophyton is the fungus that primarily infects skin and nails, but it does not infect hair. The other options, Trichophyton and Microsporum, are well-known to infect hair, causing conditions like ringworm of the scalp (tinea capitis). Trichophyton and Microsporum species have the ability to invade the hair shaft, leading to hair breakage and loss.

**Why Each Wrong Option is Incorrect**
**Option A:** Trichophyton is a common cause of hair infections, particularly in tinea capitis.
**Option B:** Microsporum is another genus that infects hair, often causing ringworm of the scalp.
**Option C:** Epidermophyton primarily infects skin and nails, not hair.

**Clinical Pearl / High-Yield Fact**
Dermatophytes can be classified into three main genera: Trichophyton, Microsporum, and Epidermophyton. Trichophyton and Microsporum species are known to infect hair, while Epidermophyton primarily affects skin and nails.

**Correct Answer: C. Epidermophyton**