Amold spore has a negative impact on the respiratory system, and molds and spores thrive in water-damaged furniture and carpets. Given these facts, what has a negative impact on the respiratory system among the following options:
- harmful substances
 - water-damaged carpets
 - a pathogens
 - lungs
 - density
 - oxygen
 - Something that causes allergies
 - some viruses


 

  water-damaged carpets       