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
 
        
             
        
        
        
There are struggles along the way
        
             
        
        
        
The statement best expresses a key idea of this passage is People should consider greeting each other with handshakes.
<h3>What is passage?</h3>
Comprehension passage refers to write ups in which questions are given in under to understand the comprehension or passage well.
Therefore, The statement best expresses a key idea of this passage is People should consider greeting each other with handshakes.
Learn more about passage below.
brainly.com/question/17000042
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Because he created a wildlife park in DePaul, did not reveal Edwar intent to help the citizens of DePaul.