A fаrmer wаnts tо knоw whаt type оf fertilizer leads to the fastest growing plants. He devises an experiment where he sets aside 3 plots, one for each fertilizer type to test his crops’ growth. All three plots receive the same amount of sunlight and water each day. One plot receives fertilizer A, one plot receives fertilizer B, and the third plot receives no fertilizer at all. Which of the following are control variables for the experiment?