Which of the following statement is true? Animals cannot be changed into petrified fossil.
The process of petrifaction is always completed.
Replacing original materials by minerals creates petrified fossils.
Petrified wood can only be found closer to the equator.

Ithink the answer is a or d.

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 .

Iam not going to tell you