**Core Concept**
Herpes simplex virus (HSV) is a double-stranded DNA virus that primarily causes infections in humans, leading to conditions like oral and genital herpes. The virus can be transmitted through direct contact with an infected individual's skin or mucous membranes.

**Why the Correct Answer is Right**
The correct answer is **A. Man** because HSV is a human-specific virus that primarily infects humans. Humans are the natural reservoir and the primary carriers of HSV, making them the primary source of transmission. This is due to the virus's ability to infect and replicate within human cells, leading to the development of symptoms and transmission to other individuals.

**Why Each Wrong Option is Incorrect**
**Option B:** Monkeys are not the primary carriers of HSV, although they can be infected with the virus. However, this is not the primary or natural reservoir for the virus.

**Option C:** Both humans and monkeys are not equally carriers of HSV. While monkeys can be infected, humans are the primary and natural carriers of the virus.

**Option D:** There are no known carriers of HSV other than humans, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
HSV can remain latent in human nerve cells for extended periods, leading to recurrent infections and transmission to others. This highlights the importance of practicing safe sex and proper hygiene to prevent the spread of the virus.

**✓ Correct Answer: A. Man**