Based on the cell theory, which of the following is true? All living and nonliving things are made of cells.
All cells are too small to be seen with the naked eye.
Small organisms have smaller cells than large organisms.
Large organisms have more cells than small organisms.

And a) oxygen i believe

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 .