In an electro-hydraulic steering system, under movement is maintained in close synchronization with the steering wheel position by means of the （）.

A.stress
B.strain
C.shear strength
D.ultimate tensile strength

A.increase discharge pressure
B.decrease pump capacity
C.decrease pump cavitation
D.decrease reaction ring clearance

A.too much superheat
B.insufficient superheat
C.suction pressure too low
D.excessive refrigerant returning to the compressor