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

Fact 2: From the bladder, urine leaves the body.

Given the two facts above, answer the question "Urine has to pass through what as the bladder empties?" with the following options: 
- epidermal
 - body water
 - a sphincter
 - all liquids
 - mouth of rivers
 - alveoli
 - salt and water.
 - aqueous solution


 

   a sphincter      