Migraine study results

the table shows the results of a study testing the effectiveness of a migraine medication. why was one group given a sugar tablet?
a. to include a control group
b. to have an experimental group
c. to provide a variety of treatments
d. to give the body additional nutrients

2. cheryl hears a new song on the radio every day during the week on her commute to work. surprisingly, when the song comes on at a party on saturday night, she knows most of the words without trying. describe the three ways that we use cognition to learn without reinforcement. which type of cognitive learning without reinforcement best explains how cheryl knew the song lyrics? explain your answer.