Which term refers to contact with a substance or environment, such as a chemical or pathogen?

• A. Expansion
• B. Etiology
• C. Exposure
• D. External

Answer: (C)

Exposure describes contact with a substance or environment, such as a chemical or pathogen. It covers how a person may come into contact with an agent and potentially absorb, inhale, ingest, or have skin contact, with risk influenced by how long, how much, and through which route the contact occurs. This concept is key for understanding risk and potential health effects, since the degree of exposure helps determine likelihood and severity of outcomes. The other terms refer to different ideas: expansion means growth or increase; etiology is the cause of a disease; external simply means something outside, not the specific act of contact with an agent.