What is the main point of paragraph 3? A Red blood cells

B the skeletal system

C the structure of a bone

D bones, cartilage, and blood vessels

C the structure of a bone

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 .