You Are Interested in the Effects of Both Alcohol and Cannabis

Multiple Choice

You are interested in the effects of both alcohol and cannabis on driving ability. So you run a between groups experiment. There are four groups: one group drinks alcohol only, one group smokes cannabis only, one group drinks alcohol and smokes cannabis, and the final group consumes no drugs at all. All participants then operate a driving simulator and you record driving speed, accidents and lane violations. You find that there are more driving problems in the group that consumes both alcohol and cannabis. In this study the independent variable is

A) alcohol
B) cannabis
C) alcohol and cannabis
D) driving speed
E) number of accidents