To Test the Effect of Background Music on Class Performance,Professor

Multiple Choice

To test the effect of background music on class performance,Professor Jones plays soft background music for his introductory class and no music for his advanced class.He counts the number of "intelligent questions" in each class and reports more in the class with music.What are the two things wrong with this experiment?​

A) Lack of an independent variable and lack of demand characteristics
B) ​Lack of a control group and lack of a dependent variable
C) ​Lack of random assignment and lack of blind observations
D) ​Lack of a hypothesis and lack of a correlation