We can solve this problem by easily by factoring. Right off the bat, we can see that this is the difference of 2 squares. The difference of two square's factored form is (a+b)(a-b), which is what this equation is in right now. But, if we want the unfactored form, then we need to do , with a being -4c and b being 3d. -4c squares. Simplifying those values, we get 16 - , which is the same as A.