An Arizona farmer investigates the method to control the Egyptian alfalfa weevil, the primary pest of alfalfa crops in southwestern Arizona. The farmer sows genetically identical alfalfa seeds on three plots
of land and harvests the alfalfa for three years and uses a different pest control method on each plot.
On plot A, the farmer does not use any pest control methods. On plot B, the farmer introduces a
parasitic wasp that uses the alfalfa weevil as its primary host. On plot C, the farmer uses an insecticide.
The farmer records the alfalfa yields for each plot after each harvest.
A. Identify the general type of pest control method used on plot B.
B. If a fourth plot D were available, explain how the farmer could modify the investigation to include an
additional pest control method.