The needle valve in a fuel valve will （） when the fuel pressure action on the needle valve tapered face exerts a force lower than that of the spring compression.

A.more water contents
B.contamination with fuel oil
C.higher temperature
D.sufficient cooling of oil mist

A.is always less than 100%
B.is always more than 100%
C.is always equal to 90%
D.is always less than 90%

A.principle
B.principal
C.cause
D.case