Fact 1: Urine leaves the body through a sphincter in the process of urination.

Fact 2: Muscles around the urethra, called sphincter muscles, control the flow of urine out of the body.

Given the two facts above, answer the question "What controls the urination process?" with the following options: 
- microorganisms
 - mechanical waves
 - that material's properties
 - the looseness of soil
 - Muscles around the urethra
 - Bones around the urethra
 - The brain
 - Muscles around the anus


 

     Muscles around the urethra    