Respuesta :
I would say (A) because it allows the bacteria (bacteria X) to be exposed to the control condition and the experimental condition so that a cause-effect relationship can be established. Here, the control condition would be the darkened area and the experimental condition would be the lightened area.
Answer:
Place a Petri dish with Bacteria X in a lighted area and a Petri dish with the Bacteria X in a darkened area, and then observe the rate of reproduction over time.
Your welcome :D