2. How does Mike's mom compare the cell membrane and the nuclear membrane?
A. Both the cell membrane and nuclear membrane are coverings.
B. Both the cell membrane and the nuclear membrane controls the cell's activities.
C. Both the cell membrane and the nuclear membrane let out waste.
D. Both the cell membrane and the nuclear membrane allow substances to enter the
cell.

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 .

Pretty sure it's d. heterogeneous is separated by physical properties.