When discussing a person running a marathon, what is the different between constant speed and average speed? Constant speed would ___________, whereas average speed would be _____________.
a. Be the runner's speed at any given instant; the runner's speed over the entire marathon.
b. Mean the runner is neither slowing down or speeding up; the runner's speed over the entire marathon.
c. Be the runner's speed over the entire marathon; the runner's speed at any given instant.