An impeller pump in an outboard motor uses an impeller made of
a. stainless steel.
b. bronze.
c. synthetic rubber.
d. brass.

The answer is (c.) synthetic rubber

The impeller pump in some outboard motor is made of synthetic rubber. The purpose of the impeller in the motor is for the cooling. It is used to pump the water to the engine from below. It has a standard design and it only uses rubber as the material.