Jason just identified the variables for his experimental investigation. What is MOST likely his next step in the scientific method?

plan the experimental treatment, including manipulating variables
decide research methodology, including manipulating variables
construct engineering designs, including manipulating variables
communicate the experimental design, including manipulating variables

Jason's next step in the scientific method is most likely to plan the experimental treatment, including manipulating variables. This involves determining the specific steps and procedures that will be used in the experiment to test the variables that have been identified.