Dan has recently begun using an addictive,euphoria-producing drug. Which of the following will probably occur if he repeatedly uses this drug?

A) As tolerance to the drug develops,Dan will experience increasingly pleasurable "highs."
B) The dosage needed to produce the desired effect will increase.
C) After each use,he will become more and more elated.
D) Dependence will become less of a problem.

As Dan repeatedly uses the addictive, euphoria-producing drug, he will develop a tolerance to it, which means that he will require a higher dosage to achieve the same effect. This is likely to lead to an increase in the dosage needed to produce the desired effect. Option A is incorrect as tolerance will result in Dan needing more of the drug to achieve the same effect, not an increase in the pleasurable experience. Option C is incorrect as after each use, Dan may feel a decrease in the elation he previously experienced. Option D is incorrect as repeated use of the drug increases the likelihood of dependence, not decreases it.