The sign that he saw read “______ without permission”.

The sign that he saw read “______ without permission”.
A、Keep up
B、Keep out
C、Keep off
D、Keep away
【正确答案】：B
【题目解析】：Keep up 保持；Keep out 阻止进入；Keep off 让开；Keep away防范；句意：他看到的牌子上写着“未经允许不得入内”。因此B符合题意。