If you get all the factors, then compare the factors of 32 and 12. 12 because that is the difference between 44 and 32.
Factors of 32: 1,2,4,8,16,32
Factors of 12: 1,2,3,4,6,12
So, notice there is NO 11 or 8 in 12. So that eliminates some answer choices. But, there is a 8 in 32, and a 3 in 12. So the answer would be a) 8-3 or b) 3-8. I cannot remember which one is correct but i think you can do that yourself. Hope this helps.