How does a volcano form a. magma at the surface hardens into metaphoric rock b. lava comes up from beneath the surface and solidifies into metaphoric rock c. magma repiditaley comes up from beneath the surface and solidifies into ingenious rock d. lava comes up from the surface and hardens into ingenious rock

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 .

Hcn is your answer my guy : )