**Core Concept**
Herpes zoster ophthalmicus (HZO) is a manifestation of varicella-zoster virus reactivation in the ophthalmic division of the trigeminal nerve, leading to inflammation and damage to the nerve and surrounding tissues. The ophthalmic division is responsible for transmitting sensory information from the eye and surrounding areas to the brain.

**Why the Correct Answer is Right**
The ophthalmic division of the trigeminal nerve (V1) is the most frequently involved in herpes zoster ophthalmicus due to its close proximity to the Gasserian ganglion, where the varicella-zoster virus resides. When the virus reactivates, it travels down the nerve fibers and causes inflammation and damage to the nerve and surrounding tissues, leading to characteristic symptoms such as eye pain, conjunctivitis, and keratitis. The ophthalmic division's involvement is often accompanied by involvement of the nasociliary nerve, which supplies the nasal mucosa and the ciliary ganglion, leading to symptoms such as tearing, photophobia, and eye pain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question as it does not specify a nerve involved in herpes zoster ophthalmicus.
**Option B:** The maxillary division of the trigeminal nerve (V2) is not typically involved in herpes zoster ophthalmicus, as it supplies the maxillary region of the face, including the upper lip, palate, and nasal cavity.
**Option C:** The mandibular division of the trigeminal nerve (V3) is not involved in herpes zoster ophthalmicus, as it supplies the lower lip, chin, and jaw.

**Clinical Pearl / High-Yield Fact**
The varicella-zoster virus can remain dormant in the Gasserian ganglion for decades after the initial varicella infection, and can be reactivated by various factors such as age, immunosuppression, and stress, leading to herpes zoster ophthalmicus.

**Correct Answer: C. Ophthalmic division of the trigeminal nerve (V1).**