What simple machine would be best for lifting a couch through a 3rd floor apartment window?

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 .

True or false:   the purpose of a defense mechanism is to get uncomfortable feelings out into the open so they can be dealt with in a healthy manner.indeed true: )