Hi. The correct answer is B. Let me explain why I came to this conclusion.
I like starting from the end of the equation to the front. As most know, when we divide exponents, we subtract them.
y^13-y^9 = y^4
x^5 + x^8=x^13
Because I can only simplify using positive exponents, I transformed ^-5 to ^+5
Now, 72/16 = 4.5. I multiplied 4.5 by 2 and came out with 9. Because I multiplied 4.5, the answer would have to be a fraction.
So now we are left with 9y^4/2x^13
