I don’t understand what is ur question
Think of an equation:
200 - 91 = 109
You can do anything to this equation, as long as you do the same thing to both sides. So, if you add 91 to both sides, you will get:
200 = 200
Since this holds true, Susan's strategy to add her answer to 91 makes sense.
The best and the most correct answer among the choices provided by the question is the first choice. The denotation for proponent is "supporters" I hope my answer has come to your help. God bless and have a nice day ahead!