Urine leaves the body through a sphincter in the process of urination, and fluids in the urine eliminate metabolic waste products. Given these facts, metabolic waste products can leave the body through among the following options:
- burning coal
 - animal transport
 - Dehydration
 - radiative transfer
 - osmosis
 - convection
 - fossil fuels
 - a sphincter


 

        a sphincter 