Meteor on the moon

This task is about how sound and light travel.

Question

Moon-view-PK.jpg
 
a)  Suppose a huge meteor crashed on to the visible part of the Moon's surface causing a massive explosion.
     What would an observer on Earth see and hear?

    • A bright flash and the loud noise of the explosion as it happened.

    • The flash of the impact followed a little later by the sound of the explosion.

    • The flash of the explosion, but no sound would be heard.

    • Nothing; the explosion would be neither seen nor heard.

b) Explain why the answer you chose is correct.