Fact 1: Skin is used for breathing air by frogs.

Fact 2: An apathetic frog is probably a sick frog.

Given the two facts above, answer the question "What largest organ can cause sickness? " with the following options: 
- Heart
 - lungs
 - immune
 - germs
 - mold
 - Skin
 - Liver
 - Stomach


 

      Skin   