Which situation is an example of an observational study? O A. Finding the number of red jellybeans placed in an average jar of
O B. Having customers fill out a questionnaire about their favorite
O c. Dividing a class into thirds, giving each third a different amount of
O D. Placing different groups of people in different colored rooms and
jellybeans by counting
brand of toothpaste
time to read, and then testing comprehension
recording their mood