The Figure Shows a Side View of a Galaxy That

The figure shows a side view of a galaxy that is 50.0 light years in diameter. This value for the diameter is its proper length. A spaceship enters the galactic plane with speed 0.995c relative to the galaxy. Assume that the galaxy can be treated as an inertial reference frame. Note: A light year is the distance that light travels through vacuum in one year; that is, 1 light year = c × (1 year) .
-How long does it take the spaceship to cross the galaxy according to an observer at rest in the galaxy?

A) 5.00 years
B) 12.5 years
C) 49.8 years
D) 50.3 years
E) 90.0 years