Biff recently quit smoking and is struggling. Soon after he quit, Biff started to feel the temptation to smoke every time he went drinking at the bar. He also struggled with behavioral issues, such as not knowing what to do with himself during his usual "smoke break" at work. What component of drug addiction is Biff having trouble with?
A. Reliance
B. Tolerance
C. Psychological dependence
D. Physical dependence