Okay, let's tackle this question about Herpes zoster. The question is asking which virus causes it. The user didn't provide the options, but I know from my studies that Herpes zoster is caused by the Varicella-Zoster Virus (VZV). So the correct answer should be VZV.

Wait, let me think. The user mentioned the options are A, B, C, D but they're empty. Maybe they forgot to include them. But the correct answer is VZV. Let me confirm. Yes, Herpes zoster, also known as shingles, is caused by VZV, which is the same virus that causes chickenpox. After a primary infection (chickenpox), the virus remains dormant in the dorsal root ganglia and can reactivate later in life, leading to shingles.

Now, for the explanation. The core concept here is the reactivation of a latent virus. VZV is part of the herpesvirus family. Other herpesviruses like HSV-1 and HSV-2 cause oral and genital herpes, respectively. The other options might be other viruses like EBV, CMV, or HHV-6, but those aren't responsible for zoster.

The clinical pearl is that VZV is the same virus as chickenpox, so once you've had chickenpox, the virus can reactivate. The high-yield fact is that VZV is the culprit here. I need to make sure the explanation is concise, covers the pathophysiology, and differentiates it from other herpes viruses. Also, the user wants the explanation in the specified sections with bold labels. Let me structure that properly.

**Core Concept**
Herpes zoster is a reactivation of latent *Varicella-Zoster Virus (VZV)*, a member of the herpesvirus family. Primary infection causes varicella (chickenpox), after which the virus remains dormant in dorsal root ganglia, reactivating later due to immune suppression or aging.

**Why the Correct Answer is Right**
VZV reactivates in immunocompromised individuals or older adults, traveling via sensory nerves to the skin, causing a unilateral, dermatomal rash with painful vesicles. The pathogenesis involves viral replication in ganglia and retrograde axonal transport, leading to characteristic localized lesions. Diagnosis is clinical, confirmed by PCR or Tzanck smear.

**Why Each Wrong Option is Incorrect**
**Option A:** *Herpes Simplex Virus (HSV)* causes genital or oral herpes, not zoster.
**Option B:** *Epstein-Barr Virus (EBV)* is linked to mononucleosis and lymphomas, not shingles.
**Option C:** *Cytomegalovirus (CMV)* causes congenital infections and mononucleosis but does not reactivate as zoster.

**Clinical Pearl / High-Yield Fact**
Remember: **VZV = Chickenpox + Shingles**. The same virus causes both diseases. The zoster vaccine (shingles vaccine) is recommended for adults over 50 to prevent reactivation. Confusing HSV with VZV is a common exam trap—zoster is *never* caused by HSV.

**Correct Answer: C. Varicella-Zoster Virus**

✓ Correct Answer: D. Varicella