Fact 1: Air pollution harms the respiratory and circulatory systems.

Fact 2: Sulfur dioxide can irritate the respiratory system and damage the heart and circulatory system.

Given the two facts above, answer the question "What organ is harmed by air pollution?" with the following options: 
- piano
 - church organ
 - heart
 - harp
 - bushes
 - animals
 - eardrum
 - lungs


 

   heart      