Who built their own microscope and looked at living things in pond water, milk, and other substances in 1683? Group of answer choices

Anton van Leeuwenhook

Robert Hooke

Matthias Schleiden

Rudolph Virchow

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 .

Ido not understand.