In the lab setup pictured below (or description), a student…

In the lab setup pictured below (or description), a student is trying to determine the effect of pollutants on the growth of three groups of seeds. The results will not be valid because the experiment is missing _________Group 1: 25 degrees C, 10 radish seeds, open Petri dish, 20mL motor oil Group 2: 35 degrees C, 10 bean seeds, sealed Petri dish, 20mL dish soap Group 3: 45 degrees C, 10 alfalfa seeds, sealed Petri dish, 20mL  antifreeze