Fact 1: Abreathing mask is used for keeping harmful particles from entering the respiratory system.

Fact 2: When mold grows in the house, it can emit particles that travel through the air.

Given the two facts above, answer the question "What can keep mold from entering the respiratory system?" with the following options: 
- vaccinations
 - layers of fat
 - deep breaths
 - sweating
 - a breathing mask
 - moisture
 - organic molecules
 - hydrogen and oxygen


 

     a breathing mask    