单选题 Which of the following drugs may be abused because of tolerance and physiologic dependence?
A. Lithium (Lithobid) and divalproex (Depakote).
B. Verapamil (Calan) and chlorpromazine (Thorazine).
C. Alprazolam (Xanax) and phenobarbital (Luminal).
D. Clozapine (Clozaril) and amitriptyline (Elavil).

【正确答案】 C

【答案解析】Both benzodiazepines, such as alprazolam, and barbiturates, such as phenobarbital, are addictive, controlled substances. All the other drugs listed aren't addictive substances.