Someone in Earth's Rest Frame Says That a Spaceship's Trip $5.78 y$

Multiple Choice

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 $5.78 y$ What is the speed of the spaceship,assuming the planets are at essentially at rest?

A) 0.816 c
B) 0.735 c
C) 0.975 c
D) 0.384 c