**Core Concept**
The question is testing the understanding of the role and responsibilities of a village health guide in primary healthcare delivery. A village health guide is a community-based health worker who provides basic healthcare services to a rural population.

**Why the Correct Answer is Right**
A village health guide is typically responsible for a population of 5,000 individuals. This is based on the World Health Organization's (WHO) recommendation for the ideal population size for a village health guide to effectively manage and provide healthcare services to the community. The guide is expected to have a thorough understanding of the community's health needs and provide basic healthcare services, including first aid, disease prevention, and health education.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it is below the recommended population size for a village health guide.
* **Option B:** This option is incorrect as it is above the recommended population size for a village health guide, making it difficult for the guide to provide effective healthcare services.
* **Option C:** This option is incorrect as it is not a feasible population size for a village health guide to manage.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the role and responsibilities of a village health guide may vary depending on the country and region. However, the recommended population size of 5,000 individuals is a general guideline used by many health organizations.

**Correct Answer: D.**