Answer:
I believe the correct answer is D.
Step-by-step explanation:
You are breathing in dinitrogen and dioxygen. You exhale dinitrogen and carbon dioxide. And the atmosphere contains traces of other gases. You drink water. You have a wash with water, and soap. You eat carbohydrates and proteins. You ride to work on a vehicle powered by hydrocarbons, which spits out carbon dioxide exhaust fumes, and also some nitrogen oxides. And so your exposure to chemicals is pervasive, and unavoidable.