Explain why there is a difference in the thickness of the crust between the side of the moon facing the Earth and the side that faces away from the Earth?

The flowers in a flower arrangement are actually alive

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 .