The answer is "c. bones".
Muscles and bones act together to frame levers. A lever is an unbending pole (for the most part a length of bone) that turns about a rotate (more often than not a joint). Switches can be utilized with the goal that a little power can move a substantially greater power. This is called mechanical advantage.
Levers can likewise be utilized to amplify development, for instance, when kicking a ball, little withdrawals of leg muscles deliver a significantly bigger development toward the end of the leg.