**Core Concept**
Erythema multiforme (EM) is a skin condition characterized by the development of target lesions, typically in response to a triggering stimulus such as infection or medication. It is a form of hypersensitivity reaction that involves the activation of immune cells and the release of pro-inflammatory cytokines.

**Why the Correct Answer is Right**
Erythema multiforme is often associated with herpes simplex virus (HSV) reactivation, which triggers an immune response that leads to the formation of target lesions. The condition is thought to result from a complex interplay between the immune system and the viral antigens, leading to the activation of T cells and the release of cytokines such as interferon-gamma and tumor necrosis factor-alpha. This results in the characteristic skin lesions and systemic symptoms associated with EM.

**Why Each Wrong Option is Incorrect**
**Option A:** EM is not typically associated with a direct bacterial infection, although it may be triggered by bacterial infections in some cases.
**Option B:** EM is not primarily a disorder of the mucous membranes, although it may involve the oral and genital mucosa in some cases.
**Option C:** EM is not typically characterized by the presence of eosinophils, although eosinophilic infiltration may be seen in some cases of Stevens-Johnson syndrome.

**Clinical Pearl / High-Yield Fact**
EM is a clinical diagnosis, and the presence of target lesions is a key diagnostic feature. It is essential to consider the possibility of EM in patients presenting with skin lesions and a history of recent infection or medication use.

**Correct Answer: C. EM is not typically characterized by the presence of eosinophils, although eosinophilic infiltration may be seen in some cases of Stevens-Johnson syndrome.