Amold spore has a negative impact on the respiratory system, and major components of the respiratory system are the lungs, trachea, nose, and the cell. Given these facts, what has a negative impact on the lungs among the following options:
- unpolluted air
 - healthy atmosphere
 - mold spore
 - smoking
 - disease
 - influenza
 - clean air
 - A virus


 

   mold spore      