The one that is a major cause of waterborne diseases is : A. Bacteria
Organisms that could cause waterborne diseases tend to have the capability to infect other object through water consumption whether it's drinking, bathing, washing, etc
Example of diseases that could be cause by these bacterias includes : Cholera, Diarrhea, Typhoid, etc
For one teens get addicted mostly through peer-pressure and two the brain becomes confused with whats wrong and whats right once you start and can't quit.