A Researcher Investigates Whether There Is a Relationship Between Hours

Multiple Choice

A researcher investigates whether there is a relationship between hours of sleep and memory for photographs by having 40 people sleep in the laboratory and waking 20 randomly selected participants after 4 hours of sleep and the others after 8 hours of sleep.After they are awakened,each participant is asked to study 12 photographs and then recall as many details from the photographs as possible.What is the independent variable in this study?

A) number of details recalled from photographs
B) hours of sleep
C) sleeping in the laboratory
D) there is no independent variable;the study is correlational