Normally, Urine Is Prevented from Backing Up into the Ureters

Multiple Choice

Normally, urine is prevented from backing up into the ureters from a full bladder due to:

A) gravity.
B) hydrostatic pressure from the renal pelvis.
C) sphincters (anatomical valves) at the junctions of the ureters and bladder.
D) physiological valves where pressure in the bladder compresses oblique openings into the ureters.