In Science Fiction Movies,it Is Common to Use a Space

Multiple Choice

In science fiction movies,it is common to use a space craft to travel across the Milky Way Galaxy or to assert that we have been visited by alien space craft from the other side of the Milky Way Galaxy.If one has a space craft that can travel at the speed of light,to an observer on the earth,how long will it take to go from one edge of the Milky Way Galaxy to the other and return?

A) 4.6 years
B) 9.2 years
C) 1000 years
D) 15,000 years
E) 150,000 years