这里的'd better是would better,还是should better?

问题描述:

这里的'd better是would better,还是should better?
W:I'm afraid I've had a terrible row with my boss.What shall I do?
M:I think you'd better apologize.
我不明白这里的'd better 是would better的缩写,还是should better的缩写,

had better的意思,最好