Punctuations are used in a sentence to organize and structure it properly. Moreover, it is used to create clarity and sense or to stress in a sentence. For example quotation marks " ", full stop (.), commas and so on.
Commas are frequently used punctuation in a sentence, hence they are used to create a short pause in a sentence.
In the above sentences, the sentence which is punctuated correctly is C. After they rested a few days, the aliens revived sufficiently to explore.
When starting with the dependent clause, the sentence is punctuated after the dependent clause. In the above sentence dependent clause is <em>“After they rested a few days”</em>, hence as compared to other sentences it is punctuated correctly.
Generally with an executive summary
telling the purpose of the report and aims and objectives
Life is not easy because people go through serious obstales
The speech was enthusiastic and got the team excited that they could win the game. Someone at a theme park would be most ebullient because they would be most enthusiastic from having fun.