When can an adult be quite sure he has stayed away from his drinks?
选项：

A:At 5 pm., if he drinks 4 standard drinks at lunchtime.
B:At 6 pm., if he drinks 5 standard drinks at lunchtime.
C:At 8 am., if he drinks 5 standard drinks the night before.
D:At 7 am., if he drinks 6 standard drinks the night before.