Correct answer # 2: The world's nations must cooperate; one nation cannot solve the world's problems by itself.
When you connect two related independent clauses or sentences you use a semicolon. Both sentences should be completed grammarly writtend and with a connection. Make sure you do not write a capital letter after the semicolon, unless it is a proper name.
Answer # 3 is incorrect as there is a capitalized word
Answer # 1 it is incorrect to use "for" as the sentence is grammarly completed
Answer:
Better Get Ready For the Judgment
Gabe's song, "Better Get Ready For the Judgment," and his hallucination that hellhounds are in Troy's yard warn Troy to change his behavior unsuccessfully because Troy does not hear the message.