A group of researchers wanted to measure the impact of playing classical music at bedtime to infants. They choose 20 infants to play music from 6:30 - 7:30 pm at bedtime and 20 infants to not play music at all. For each day for 3 months they observed them for 4 hours and recorded exactly how long it took for them to fall asleep. At the end of the 3 months they calculated the percentage of awake time to the time they slept for the 4 hours and compared the percentages to infants that had music played versus infants that did not.ExperimentalSurveyObservational StudyNone of the answer choices