You are presented with the question "What harms the respiratory and circulatory systems?" and the following answer choices: 
- Greenhouse gasses
 - burning coal
 - inoculation
 - incinerated mercury
 - fossil fuels
 - water vapor
 - Sulfur dioxide
 - air

Now knowing that air pollution harms the respiratory and circulatory systems and incinerated mercury pollutes the air, choose the best answer.


 

    incinerated mercury     