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 equipped with a stick shift and a gas pedal.The object is to maximize the distance covered by driving as fast as possible on a winding road while avoiding rear-end collisions.Some of the subjects smoke a real cigarette immediately before climbing into the driver's seat.Others smoke a fake cigarette without nicotine.You are interested in comparing how many collisions the two groups have.In this study,the cigarette without nicotine is:

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