Question

which sentence is punctuated correctly? the aliens suffered from exhaustion, after traveling several light years. they needed some relaxation, when they finally landed their spaceship. after they rested a few days, the aliens revived sufficiently to explore. they needed all their energy, once they started hiking the rough terrain.

Answer 1

The sentence that is punctuated correctly is, After they rested a few days, the aliens revived sufficiently to explore. This sentence is a complex sentence consisting of an independent and dependent clause. When the dependent clause comes first, a comma should be used to introduce the independent clause. The rest of the given sentences above need not to be separated with a comma. 

Answer 2

It would be C, After they rested a few days, the aliens revived sufficiently to explore.