Which is an example of the electromagnetic force? - A compass needle points north toward earths magnetic pole
- An iron nail rolls off a table and falls to the ground
- the moon pulls on the water in earths oceans, causing tides
- protons that make up a nitrogen atom stays together in the nucleus

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 .

Afraidsugar lol it’s the third one