Sonja Conducts an Experiment to Determine Whether Listening to Music

Multiple Choice

Sonja conducts an experiment to determine whether listening to music affects emotional state. She has children wait alone in a room that either did or did not have music playing and then has them complete a questionnaire asking about their current level of happiness. The independent variable in this study is

A) how happy they were before the study began.
B) being alone in the room while waiting.
C) whether or not music was playing in the room.
D) their level of happiness as rated on the questionnaire.