Answer: 
The correct answer is A. You can receive instant feedback from your audience.
Explanation: This is something that cannot be done if you are writing a text and your audience reads it at their home - they cannot immediately let you know what they think about your ideas and arguments. However, if you are giving a speech in front of an audience, then they absolutely can. B, C, and D are examples of what happens during writing, rather than speaking. 
 
        
                    
             
        
        
        
Answer:
C.
“If there is any practical use for helium other than medicine, laws should change to protect current supplies of the gas.” This sentence summarizes one of the major points of the argument, which is that helium reserves are in low supply.
 
        
                    
             
        
        
        
Answer:
I mean depends what the interpretation is.
 
        
             
        
        
        
Answer:
It foreshadows the end of the passage.
Explanation: