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

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

Centrifugal pumps utilize a volute casing to convert the high velocity of the fluid leaving the impeller into pressure energy. Propeller pumps, which are axial flow machines, rely on the lift generated by the propeller blades to move fluid and do not incorporate a volute for pressure conversion.