Which option identifies the most likely testable question in the following scenario? One thousand mice are separated into two groups. Flve hundred are given an artificial sweetener, aspartame, in their food. The other five hundred are given the same food without the artificial sweetener added. Once a week for six months, the mice in both groups are weighed. Will aspartame change the taste of food? Do mice enjoy eating food with aspartame? Does aspartame cause changes in the weight of mice? Do heavier mice eat more food with aspartame?