Answer:
1.) The Miracle Grow - You controlled how much went into each group.
2.) The size of the Tomato plants - It corresponds to how much Miracle Growth you put in.
3.) -> The water, it was not changed through the experiment.
-> The sunlight, it was also not changed through the experiment.
-> The amount of tomato seeds, there were never more than 10 per group.
4.) Group A, as it does not have any Miracle growth, and you can determine how much the Miracle Grow helped with the other groups through group a.
Hope this helped! And please give Brainliest.