The word "pervasive" (Line 1, Paragraph 2) might mean ______.

A．substances can alter our bodily or mental functioning if illegally used
B．"drug abuse" is only related to a limited number of drug takers
C．alcohol and tobacco are as fatal as heroin and cocaine
D．many substances other than heroin or cocaine can also be poisonous

A．tends to be superficial and artificial
B．is generally well kept up in the United States
C．is always understood properly
D．has something to do with the busy tourist trails