Final answer:
The act of releasing urine is known as micturition or urination. It involves both involuntary and voluntary actions by the urethral sphincters. The correct option is b.
Step-by-step explanation:
The act of releasing urine is known as micturition, which is also referred to as urination or voiding. It involves a combination of involuntary and voluntary actions by the internal and external urethral sphincters.
When the bladder volume reaches around 150 mL, an urge to void is sensed, and voluntary control of urination relies on consciously preventing relaxation of the external urethral sphincter to maintain urinary continence.
As the bladder fills, subsequent urges become harder to ignore, and voluntary constraint fails with resulting incontinence when the bladder volume approaches 300 to 400 mL. The correct option is b.