There are two common types in page replacement algorithm : stack and non-stack strategies. When a real page number increase only stack algorithm can increase the hit rate monotonously. In the following replacement algorithm, which one belongs to non-stack strategy

A． FIFO

B． LRU

C． OPT

D． non of above

起重机轨道的接地电阻，以及起重机任一点的接地电阻不应大于４Ω。