You are right sir.

I fixed the stem. It should be , of course, y>x >N>2 and not as stated x>y

Maybe a typo in the original sentence, otherwise is impossible to have N >0

Thanks

here y>x>N>2 so N, x, y all has to be positive number.
so N=y-x thus N^2=(y-x)^2
and quantity B is x^2+y^2 so writing it y^2+x^2 and using a^2+b^2 formula (y-x)^2+2yx.
Thus 2yx is the extra number respective to the quantity A and y and x is both positive and the whole 2yx is positive So when a positive number is added then the quantity has to be greater than the other. So correct answer is B.