You Are Tasked with the Job of Finding Out If

You are tasked with the job of finding out if two proposed changes affect ice cream sales by conducting an experiment to test the effects of proposed changes on consumer preferences. One proposal is to add more chocolate chips to the chocolate chip flavor of the ice cream. The other proposal is to use real vanilla in all the ice cream flavors (currently, the company uses artificial vanilla flavoring). Both proposals cost the company money, so they want you to determine if either proposal increases consumer preference for the ice cream to decide if these additions are worthwhile. What is/are the independent variable(s) in this experiment?