I believe the answer is D.
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
D. an article in Newsweek magazine which sentence is an example of formal language
Is this from the book Things Fall Apart?
The answer is 3, using words in a certain way to persuade the reader.
