four years, space travels was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. this inability of a rockets to provide propulsion is because_______________.

a. space is avoid the air so the rockets have nothing to push off of.
b. gravity is absent in space
c. space is void of air and so there is no air resistance in space.
d. nonsense! rockets the accelerate in space and have been able to do so for a long time
explain the answer:__________​