22. High-speed, multi-cylinder, diesel engines commonly use counterweights placed opposite to the crankpins to __________.

Counterweights on high-speed diesel engines balance centrifugal forces, reducing vibration and bearing loads. This dynamic balance is achieved by equalizing the mass distribution around the crankshaft, making option B the correct answer. Other options address related but secondary effects, such as bearing loads, reciprocating inertia, or rocking couples.