When planning and running an experiment, it is important to identify all potential variables and then make sure that most of those variables don't change during the experiment. Which best explains why this is so?

Select the correct answer. which statement applies only to the axial skeleton, not the appendicular skeleton? a. it contains a pivot joint. b. it has muscles attached that work in pairs. c. it contains red bone marrow. d. it possesses fossa for bone articulation. e. it protects the heart and lungs.