454. Trapped air was bled from the hydraulic system of a diesel engine governor while it had been operating at idle speed. Oil was added to restore the correct level and the air vent plug tightened. The compensating needle valve should then be gradually __________.

A. opened until hunting is eliminated
B. closed until it is approximately 1/16 of a turn open
C. closed to cause the engine to hunt in order to purge trapped air from the new oil
D. closed until engine hunting is eliminated