Which option is an example of a survey?
A. Having customers fill out a questionnaire about their favorite
brand of toothpaste
B. Testing the effectiveness of a mouthwash by allowing one group
to use it and comparing the results with those of a group that
doesn't use it
C. Finding the number of red jellybeans in an average jar of jellybeans
by counting
D. Placing different groups of people in different colored rooms and
recording their mood