Which of the following factors is considered part of the physical environment affecting health?

The presence of water reservoirs is a critical factor in the physical environment affecting health because it directly influences water availability and the quality of the water supply in a community. Clean and accessible water resources are vital for hydration, sanitation, and preventing waterborne diseases, which can significantly impact population health. The location and condition of water reservoirs also play a role in influencing other environmental factors such as hygiene practices and food safety.

In contrast, access to healthcare, community poverty levels, and access to educational resources are more social determinants of health rather than physical environmental factors. While these elements are crucial in understanding overall health outcomes, they do not pertain directly to the natural or built environment, which includes aspects like water resources, air quality, and housing conditions. Thus, the presence of water reservoirs is specifically tied to the physical environment, making it the correct choice in this context.