Answer the following question given this paragraph: 

Bacterial infections of urinary organs, especially the urinary bladder, are common. They are called urinary tract infections. Generally, they can be cured with antibiotic drugs. However, if they aren’t treated, they can lead to more serious infections and damage to the kidneys.


Q: Antibiotic drugs are usually effective in treating what kind of infections?

 Choices:

- viral

- lethal

- biological

- bacterial

A:
bacterial
