Answer:
The correct option is: a. Trigone
Explanation:
The trigone is the smooth triangular region that forms the floor of the urinary bladder above the urethra and consists of smooth tissues for the easy flow of urine. The trigone is connected to the two ureters and the urethra.
The trigone is very sensitive to expansion. Once expanded to a certain extent it signals the brain for the excretion of urine through the urethra.
