The earths plates moved over millions of years, bringing contenents and others freatures of the earth to their present arrangement. this movement of the lithospehers is explained by . a. continental drift b. the principal of superposition c. the theory of plate tectonics d. nuclear fission

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.