Does exposure to classical music (through instrument lessons or concert attendance) improve children's scholastic performance? In a study, researchers measured the amount of exposure to classical music for many children, along with their scores on the state's academic proficiency exam. The response variable in this study is
a.
whether a child passed the state's proficiency exam.
b.
the amount of a child's exposure to classical music.
c.
the type of instrument a child plays.
d.
the child's score on the state's proficiency exam.