30. A student builds a simple electric circuit. What are the main types of energy produced in this circuit when the switch is closed?

A thermal and light

B sound and thermal

C light and magnetism

D magnetism and sound

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .