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

ACARS的功用是（）

A.以模拟形式在飞机和地面台站之间。

B.以数字格式在飞机和地面台站之间。

C.以模拟形式和数字格式在飞机和地面台站之间。