You are presented with the question "Metabolic waste products can leave the body through" and the following answer choices: 
- burning coal
 - animal transport
 - Dehydration
 - radiative transfer
 - osmosis
 - convection
 - fossil fuels
 - a sphincter

Now knowing that urine leaves the body through a sphincter in the process of urination and fluids in the urine eliminate metabolic waste products, choose the best answer.


 

        a sphincter 