Professor nguyen is thinking about using an experimental design to study the impact of mood on reading comprehension. she is going to use two different groups: one will be manipulated to be in a happy mood, the other will group will be the control group. professor nguyen will then measure the participants' understanding of a short text using a reading comprehension score, which would be considered the variable. choose the correct answer from the following choices, and then select the submit answer button. dependent

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.