The differentiable function h(t) gives the height of a rocket, in meters, t seconds after launch. Explain the meaning of the statement h'(20)=510.
a. The rocket's acceleration at 20 seconds is 510 m/s².
b. The rocket's height at 20 seconds is 510 meters.
c. The rocket's velocity at 20 seconds is 510 m/s.
d. The rocket's initial height at launch is 510 meters.