Here is the answer to the given question above. Based on the given sample sentences, the best way to combine the sentences using a semicolon would be this: <span>The world’s nations must cooperate; one nation cannot solve the world’s problems by itself. The correct answer would be the second option. Hope this helps.</span>
'Before they ate a snack' is the correct answer, it is the adverbial clause of time. A cannot be correct because that is an independent clause, and adverb clause has to be dependent. B isn't a clause at all.
