Choose your answer from:
[i] burning coal;
[ii] animal transport;
[iii] Dehydration;
[iv] radiative transfer;
[v] osmosis;
[vi] convection;
[vii] fossil fuels;
[viii] a sphincter;

Fact 1: Urine leaves the body through a sphincter in the process of urination. Fact 2: Fluids in the urine eliminate metabolic waste products. Given the two facts above, metabolic waste products can leave the body through?
Answer:
[viii]