The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have dropped substantially in 1987.

The argument in the passage depends on which of the following assumptions?

• AThe supply of illegal drugs dropped substantially in 1987.  
• BThe price paid for most illegal drugs by the average consumer did not drop substantially in 1987.  
• CDomestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country.  
• DThe wholesale price of a few illegal drugs increased substantially in 1987.  
• EA drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.