A researcher is studying the relationship between hours of sleep and academic performance. They collect data from students on their average sleep duration and their GPA, then analyze whether these two variables tend to change together. This type of study is known as a(n):

The correct answer to the question "A researcher is studying the relationship between hours of sleep and academic performance. They collect data from students on their average sleep duration and their GPA, then analyze whether these two variables tend to change together. This type of study is known as a(n):" is Option C: Correlational study.

The other options — A) Experimental study, B) Case study, D) Naturalistic observation — are incorrect for this CLEP Exam Prep question. As explained above: A correlational study examines the statistical relationship between two or more variables, determining if they co-vary, without manipulating any variable or establishing cause and effect.