Q: What harms the respiratory and circulatory systems?\nOptions:\n- (A) Greenhouse gasses\n- (B) burning coal\n- (C) inoculation\n- (D) incinerated mercury\n- (E) fossil fuels\n- (F) water vapor\n- (G) Sulfur dioxide\n- (H) air
Let's think step by step below.

User
Air pollution harms the respiratory and circulatory systems. Incinerated mercury pollutes the air. Incinerated mercury harms the respiratory and circulatory systems.
Thus, the answer is (D).
Assistant