Final answer:
Tolerance to the effects of smoked marijuana refers to the need for chronic users to smoke more marijuana to achieve the same desired effects.
Step-by-step explanation:
Tolerance to the effects of smoked marijuana refers to the diminished response that occurs with repeated use, meaning that it takes higher doses to achieve the same desired effects. Option C is correct, as chronic marijuana users may need to smoke more marijuana to experience the same level of euphoria they initially felt when they started using the drug. This is due to the body building tolerance to the drug and needing larger amounts to achieve the desired effect.