One of the main differences between a propeller pump and a centrifugal pump is the absence of a __________.

Correct Answer: Option C — volute in the propeller type pump

Propeller pumps are axial-flow machines that utilize lift generated by blades rather than the centrifugal force and velocity conversion found in radial-flow pumps. Consequently, they lack a volute casing, which is the characteristic spiral-shaped housing used in centrifugal pumps to convert kinetic energy into pressure head.