Which statement about reaction rates is true? (a)changing the temperature cannot speed up a reaction rate. (b)changing the amount of reactants will not change the reaction rate. (c)changing the surface area affects the reaction rate. (d)a catalyst slows down the reaction rate.

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 .

6because i no yea yea