HEL Base your answer to questions 6-8 on the information below and on your knowledge of Living Environment.
A student designed an experiment to investigate a claim that athletes would have lower heart rates than nonathletes during exercise. After the students classified themselves as an athlete or a nonathlete, their resting pulses were determined. Then all the students performed the same exercise for four minutes and their heart rates were determined by recording the pulse rate in beats per minute. The students continued to measure their pulse rates for an additional four minutes. The average heart rate per minute for each group was determined. The data were recorded, as shown on the table below.

6. Write a hypothesis for the experiment described above.

7. Which statement is best supported by the data in the chart?
A. After exercise, the nonathletic students had a lower heart rate than the athletic students.
B. After exercise, the heart rates of the athletic students returned to resting pulse in four minutes.
C. During exercise, both groups of students had the same increase above their resting pulse.
D. During exercise, the athletic students had a higher heart rate than the nonathletic students.

8. To improve the validity of the conclusion reached in this experiment, the students should repeat the experiment
A. disregarding any data that don’t fit the hypothesis with a larger number of athletes and nonathletes
B. comparing the heart rates and breathing rates of males and females with the athletes doing different exercises than the nonathletes