Two Blinking Warning Lights Are $1000 \mathrm{~ns}$ Apart Along a Railroad Track

Multiple Choice

Two blinking warning lights are $1000 \mathrm{~ns}$ apart along a railroad track. A train moves from west to east at a speed of 0.5 . In the train frame, an observer registers flashes from each light, and after correcting for light travel time, concludes that the east light flashed 200 ns before the west light flashed. Which light flashed first in the ground frame? (Hint: Draw a space time diagram.)

A) The east light flashes before the west light.
B) The west light flashes before the east light.
C) The lights flash simultaneously.
D) One does not have enough information to say.