The triangular area of the urinary bladder between the two ureters posteriorly and the urethra anteriorly is the

The triangular area of the urinary bladder between the two ureters posteriorly and the urethra anteriorly is the 





A) external urinary sphincter.
B) internal urinary sphincter.
C) smooth muscle.
D) transitional epithelium.
E) trigone.








Answer: E