Which type of muscle is responsible for moving fluids through the urinary system?

Smooth muscle is the correct choice because it is the type of muscle tissue that is found in the walls of hollow organs, including the urinary system. This category of muscle operates involuntarily, meaning it is not under conscious control. In the urinary system, smooth muscle fibers are involved in the process of peristalsis, which helps move urine from the kidneys down the ureters to the bladder and eventually out of the body.

Cardiac muscle, while also involuntary, is specialized for the heart and not involved in the urinary system. Skeletal muscle, on the other hand, is under voluntary control and is responsible for movement of the skeleton rather than moving fluids. Striated muscle is a term that encompasses both skeletal and cardiac muscle due to their striated appearance under a microscope. However, since urinary fluid movement is specifically handled by smooth muscle, it is the most appropriate answer in this context.