Lizette works in her school’s vegetable garden. Every Tuesday, she pulls weeds for 15 minutes. Weeding seems like a never-ending task. Each time Lizette goes to the garden, there are just as many weeds as the week before! Lizette’s teacher suggests that she use a strong solution of vinegar to kill the weeds. Vinegar is acidic and prevents plants from maintaining homeostasis. Lizette sets up a controlled experiment to test her hypothesis that the solution will kill the weeds without harming nearby vegetables. She plans to spray one group of weeds with the solution and another group of weeds with water as a control.

What variables should Lizette keep the same between the control group of weeds and the sprayed weeds?