Urine leaves the body through a sphincter in the process of urination.
Urination requires relaxation of the sphincter muscle.
Urine leaves the body upon relaxation of a muscle.
What leaves the body upon relaxation of a muscle?

(A) sweat
(B) urine
(C) Energy.
(D) Energy
(E) fat
(F) lead
(G) blood
(H) gasoline