Final answer:
The hollow, muscular sac that holds and stores urine is the bladder, fulfilling its role in the urinary system.
Step-by-step explanation:
The hollow, muscular sac that holds and stores urine is the bladder. Its primary function is to collect urine from the kidneys via the ureters.
The bladder is lined with transitional epithelium and has walls that can expand and contract. When one needs to urinate, the detrusor muscle contracts, the internal urethral sphincter relaxes, and urine is released into the urethra, leading to the exterior of the body.
Therefore, the correct answer to the given multiple-choice question is option 2) Bladder.