In a Laboratory, Smokers Are Asked to Drive Using a Computerized

Multiple Choice

In a laboratory, smokers are asked to drive using a computerized driving simulator and cover the maximum distance possible, while avoiding rear-end collisions. Some volunteers are given a real cigarette to smoke immediately before the test. Others smoke a fake cigarette without nicotine. The number of collisions the two groups make is to be compared. In this study, the cigarette without nicotine is a:

A) dependent variable.
B) placebo
C) double-blind procedure.
D) hypothesis.