**Core Concept**
Toxic epidermal necrolysis (TEN) is a severe skin condition characterized by widespread skin necrosis and detachment. It is often triggered by medications, particularly antiepileptic drugs (AEDs) and nonsteroidal anti-inflammatory drugs (NSAIDs). The pathophysiology of TEN involves an immune-mediated reaction, leading to the activation of cytotoxic T cells and the release of pro-inflammatory cytokines.

**Why the Correct Answer is Right**
Phenytoin, a hydantoin derivative, is one of the most common AEDs implicated in causing TEN. The exact mechanism of phenytoin-induced TEN is not fully understood, but it is thought to involve an abnormal immune response to the drug, leading to the activation of CD8+ T cells and the release of tumor necrosis factor-alpha (TNF-alpha). This results in the apoptosis of keratinocytes and the subsequent detachment of the epidermis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Carbamazepine is another AED that can cause TEN, but it is not the most commonly implicated drug.
* **Option B:** Valproic acid is less commonly associated with TEN compared to phenytoin and carbamazepine.
* **Option D:** Lamotrigine can cause Stevens-Johnson syndrome (SJS), a milder form of TEN, but it is not the most commonly implicated AED in TEN.

**Clinical Pearl / High-Yield Fact**
Remember the "Naranjo algorithm" to assess the likelihood of a drug causing an adverse reaction, including TEN. The algorithm considers factors such as the time to onset, dose, and alternative causes of the reaction.

**Correct Answer:** C.