Which of the following sentences is correct?
选项：

A:If you start to feel nervous or stressful,do not reach for a cigarette.
B:Don’t choose a day that you know it is going to be stressful,such as the day of an exam.
C:It is only when the disease has progressed to AIDS that a person begins to look sick.
D: Anyone who has sex with a person infected with HV/AIDS risks to get the virus.