Someone in Earth's Rest Frame Says That a Spaceship's Trip

Someone in Earth's rest frame says that a spaceship's trip between two planets took 10.0 y, while an astronaut on the space ship says that the trip took 6.27 y. Find the speed of the spaceship in terms of the speed of light.

A) 0.779c
B) 0.687c
C) 0.975c
D) 0.384c