Answer:
The correct answer is a inducer(lactose) = acts by stepping on the gas pedal.
Explanation:
In lac operon lactose act as an inducer.Lactose exerts its action by binding with the repressor and inducing a conformation al change in the repressor molecule and prevent the later from binding to the operator region.
This ultimately result in the expression of the structural genes such as Lac Z ,Lac Y and Lac A.
According to the given question if the lac operon is described using a car analogy then the inducer lactose will act by stepping on the the gas pedal and this is the positive regulation of Lac operon.