Which Statement Best Explains Why Drugs Users Need More and More

Which statement best explains why drugs users need more and more of the drug to reach the same level of pleasure?

A) As dopamine receptors are reduced,more of the drug is required to ensure the remaining receptors are occupied.
B) As dopamine receptors increase in number,more of the drug is required to fill the empty receptors.
C) Natural dopamine production is increased;therefore,more drugs are required to increase receptor sites.
D) Dopamine receptors stop producing dopamine;therefore,more drugs are required to increase receptor production.
E) As dopamine production is reduced,more of the drug is required to ensure that the remaining receptors are occupied.