Harm to the respiratory and circulatory systems can come from \nOptions:\n- (A) Greenhouse gases\n- (B) hydrocarbons\n- (C) Sulfur dioxide\n- (D) nitrogen oxides\n- (E) burning coal\n- (F) fossil fuels\n- (G) emissions\n- (H) Greenhouse gasses
Let's think step by step below.
(D)
Air pollution harms the respiratory and circulatory systems.

Nitrogen oxides cause air pollution.

Nitrogen oxides harms the respiratory and circulatory systems.

.

The answer: (D)