Why is it important to guard against unexpected variables in a study? a) To insure that a study is not biased by the researcher
b) To insure that an experiment is valid
c) All of these
d) To understand the obstacles that could change your placebo

Role models are really important too, because they influence you.

Ansinterlock;

Cardiorespiratory fitness is vital to lifetime fitness as it has the ability to deliver proper nutrients like oxygen to the different organs of the body and it also removing waste products every prolong physical exercise. a happy heart also does reduces the risk of many diseases which is the answer.

Unborn i am pretty sure