Fact 1: Amold spore has a negative impact on the respiratory system.

Fact 2: Respiratory symptoms include difficulty breathing, wheezing, and stridor.

Given the two facts above, answer the question "A mold spore has a negative impact on what?" with the following options: 
- vehicles
 - humans
 - breathing
 - gasoline
 - dirt
 - disease
 - rocks
 - cells


 

   breathing      