In 726 a. d., byzantine emperor leo iii banned the use of icons, or religious images. this became a controversial issue because not all byzantines agreed with the ban. this was one of several controversies that contributed to the a. weakening of the church and the rise of islam within the byzantine empire. b. byzantine empire's creation of the separation of church and state. c. banning of the practice of any religion other than christianity in the empire. d. split between the roman catholic church and the eastern orthodox church.

The authors of the paper "fudging the numbers: distributing chocolate influences student evaluations of an undergraduate course"† carried out a study to see if events unrelated to an undergraduate course could affect student evaluations. students enrolled in statistics courses taught by the same instructor participated in the study. all students attended the same lectures and one of six discussion sections that met once a week. at the end of the course, the researchers chose three of the discussion sections to be the "chocolate group." students in these three sections were offered chocolate prior to having them fill out course evaluations. students in the other three sections were not offered chocolate. the researchers concluded that "overall, students offered chocolate gave more positive evaluations than students not offered chocolate." indicate whether the study is an observational study or an experiment. give a brief explanation for your choice.