According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey.


WHY IS D INCORRECT?

A doubling those reported in the 1977 survey
B to double the number the 1977 survey reported
C twice those the 1977 survey reported
D twice as much as those reported in the 1977 survey
E twice the number reported in the 1977 survey