Answer :
the answer is D because that's 5 more than one (half the square of her own age) ;)
so the way that i would solve it is i would take 8 and square it which would equal 64 then devide it by 2 and that gives me 32 and then add 5 which gives me 37 and thats how i would get the answer. (8^{2}=64 /2=32+5=37)