The correct answer is (C) To free, detach, or release (oneself) from attachment, connection, obligation, pledge, or engagement. To break loose, separate, loosen, unfasten. To cause the gears of a motor vehicle to stop supplying torque to the axles and wheels. To remove troops from combat, to break off action.

Examples of use:

• He disengaged the drive mechanism.
• After three days of continuous fighting, the armies disengaged.