Unnithan, Houser, and Fernhall (2006) Were Interested in Whether Playing

Unnithan, Houser, and Fernhall (2006) were interested in whether playing the game Dance Dance Revolution (DDR) met the American College of Sports Medicine recommendations for exercise to improve cardiovascular health.Twenty-two adolescents, 10 of whom were classified as overweight and 12 of whom were not overweight, played DDR for 12 minutes.During the 12 minutes, the researchers measured each participant's heart rate.On average, the researchers found no difference between the heart rates of the two groups.Both groups' heart rates were above the minimum recommended for cardiovascular exercise.What is the sample in this study?

A) the 22 adolescents who participated in the study
B) all adolescents, both overweight and not overweight, who play DDR
C) the average heart rate for an adolescent playing DDR
D) the recommendation by the American College of Sports Medicine