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.

Which blood vessel contains the least amount of urea?

Which of the following enters the hilum of the kidney?

Each nephron has two parts, which are

In the kidney,the ureter,blood vessels,and nerves enter through the ..........