Carmen conducted an experiment to determine if listening to different types of music would affect a person’s pulse. Her hypothesis was that pulse rate would change with different types of music. Each person listened to seven different selections of music for 30 seconds each. Each person’s pulse was taken before the music and then after each 30-second interval of music. The pulses were taken again after the music selections were completed. Based on her experiment, Carmen concluded that a person’s pulse rate changed when the person listened to different types of music
What can Carmen do to make her experiment more reliable?
A. add another variable to test
B. repeat the experiment several times
C. decrease the amount of time the test subjects are exposed to the music
D. putting each test subject in a different location while they listen to the music