The Enterprise and the Supernova - Solution

1. E
2. A
3. In the Enterprise frame, the supernova explosion S is simultaneous with D and G which come after E. Therefore, the Enterprise arrives at the planet before the star goes supernova.
4. In the planet frame, the supernova explosion S is simultaneous with F which comes before E. Therefore, the Enterprise arrives at the planet after the star goes supernova.
5. The light from the supernova explosion S reaches the planet at C which is after E. So by that time the students would have been picked up by the enterprise and well on their way to safety. The light catches up with the enterprise at H, which is when the students will finally see what they were escaping from.