**Core Concept**
Griseofulvin is an antifungal medication that works by inhibiting the growth of fungi by interfering with the microtubule function in fungal cells. It is primarily used to treat dermatophyte infections such as onychomycosis.

**Why the Correct Answer is Right**
Griseofulvin is given for a prolonged period to ensure that the drug is incorporated into the nail plate, which grows slowly. The treatment duration is typically 4-6 months to allow for the complete replacement of the infected nail plate with a new, healthy one. This prolonged treatment period is necessary because griseofulvin does not penetrate the nail plate itself, but rather the nail matrix, which is the area beneath the cuticle where new nail growth occurs.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is too short and would not allow for the complete replacement of the infected nail plate.
**Option B:** This option is too long and may increase the risk of side effects without providing additional benefit.
**Option C:** This option is not specific to the treatment of onychomycosis and may not be effective for this condition.

**Clinical Pearl / High-Yield Fact**
Griseofulvin is most effective when given concomitantly with a keratolytic agent, such as urea or salicylic acid, to help soften the nail and facilitate penetration of the drug.

**Correct Answer:** C.