While Discussing Pulleys, Technician a Says That Some Engines Use

While discussing pulleys, Technician A says that some engines use a vibration damper to minimize vibrations in the crankshaft that could cause it to crack or break. Technician B says that some engines do not use a damper. Instead they have a single-piece pulley with threaded holes to attach the drive belt pulley(s) . Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B