Which blood vessel contains the least amount of urea?

Which of the following statements is correct?

Given below are two statements:
Statement $I$: At the base of the urinary bladder,there is an inverted triangular area called the trigone.
Statement $II$: Three layers of dartos tunic muscles are present in the wall of the urinary bladder.
In the light of the above two statements,choose the correct option.

Kidneys lie outside the peritoneum,hence they are called

Describe the human excretory system.

Which of the following enters the hilum of the kidney?