Choices: (A). energy of moving objects. (B). mining gold. (C). Warm air moving into cold air. (D). burning fossil fuels. (E). acid rain. (F). melting ice caps. (G). energy usage. (H). single-celled organisms.
Given those answer options, answer the question: Fact 1: Burning fossil fuels increases the carbon in the atmosphere. Fact 2: This atmospheric carbon might be contributing to the greenhouse effect. Given the two facts above, what is contributing to the greenhouse effect?
A:
(D).