**Core Concept**
One Village Health Guide (VHG) is a community health worker responsible for providing primary health care to a specific population in a rural or underserved area. The VHG plays a crucial role in bridging the gap between the community's health needs and the availability of health services.

**Why the Correct Answer is Right**
The VHG is typically responsible for a population ranging from 5,000 to 10,000 individuals. This population size allows the VHG to effectively identify and address the health needs of the community, provide preventive care, and refer complex cases to higher-level healthcare facilities. The VHG's role is to promote health, prevent disease, and provide basic curative services to the population.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a sub-center is typically responsible for a population of 5,000 in plain areas and 3,000 in hilly, tribal, or difficult areas.
**Option B:** This option is incorrect because a Primary Health Center (PHC) is responsible for a population of 30,000 in plain areas and 20,000 in hilly, tribal, or difficult areas.
**Option C:** This option is incorrect because a Community Health Center (CHC) is responsible for a population of 80,000 in plain areas and 40,000 in hilly, tribal, or difficult areas.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the population size and the type of healthcare facility are closely linked, and each level of healthcare facility has a specific population size it is designed to serve.

**Correct Answer: C. 80,000 in plain areas and 40,000 in hilly, tribal, or difficult areas.**