During a Dissection, Arnie Saw the Ureters Entering the Lateral

Multiple Choice

During a dissection, Arnie saw the ureters entering the lateral corners of the bladder but found the internal openings of the ureters in the trigone near the midline of the bladder. His observation necessarily means that

A) the ureters run medially for some distance within the posterior bladder wall.
B) the ureters and urethra are really the same tube.
C) each ureter must have four distinct openings into the bladder.
D) this bladder had a congenital defect.