A new simulation game, StateArt, is designed to simulate diplomatic, military, and trade relations among countries. The instructor of an international relations (IR) course would like to find out whether StateArt is an effective learning tool. He wonders: "Will playing StateArt cause my students to acquire a better understanding of IR subject matter?" The instructor does not make StateArt a course requirement, but he encourages voluntary participation. This volunteer group plays StateArt throughout the semester. At the end of the semester, the instructor found that, compared with nonplayers, StateArt players had performed better in the course. They had a better grasp of all covered topics, including international diplomatic, military, and trade relations. The instructor concludes: "Yes, StateArt caused my students to acquire a better understanding of IR subject matter." 1. Because of the design of his study, the instructor's conclusion is not supported. (i) Write down two rival causes that could explain why students who played StateArt performed better in the course than students who did not play StateArt. (ii) Describe how each rival cause could account for the StateArtstudent performance relationship.