It is: 91/200, because 45.5/100 is 45.5% as a fraction, but you have to make both the top a whole number, so you can multiply 45.5 by 2 to get 91, then also times the bottom by 2, and you get 200!
I believe it’s A because if you notice the rate of population grow was in the 20,000s for the US in the 1840s, while NC was hitting 600 free people at that time.