and Final Exam

Time left $1$:$54$:$42$

Two UFOs, one farther from you than the other, are flying directly towards you at high speed. While studying them through a powerful telescope, you see a flash of blue light emitted from the closer UFO, followed briefly by a flash of green light emitted from the farther UFO $($assume that your vision is ultra$-$sharp, so that you can detect even the smallest interval of time between the flashes$).$ You can conclude that in your frame,

Select one:

a$.$ the green light flash was emitted before the blue light flash.

b$.$ the two light flashes were emitted simultaneously.

c$.$ the blue light flash was emitted before the green light flash.

d$.$ there is not enough information to draw a conclusion.