What percentage of U.S.commercial buildings are considered to be "sick" due to indoor air pollutants,according to the EPA? 

A)  5% 
B)  10% 
C)  15% 
D)  20%

Indoor Air Pollutants

Substances contaminating the air inside buildings and homes, originating from sources like tobacco smoke, building materials, and indoor activities, potentially harming human health.

EPA

The Environmental Protection Agency, an organization tasked with the protection of human health and the environment by writing and enforcing regulations based on laws passed by Congress.

Commercial Buildings

Structures designed and used for business activities, such as offices, stores, and hotels.