First you simplify to 56x2 - 15x + 1.
Because of the 56, you know you will need a term with 8x and a term with 7x because 8*7=56. Answer C you can ignore because that won't give you a x^2, so it's between A and B.
The +1 in the simplified polynomial has to come from the multiplication of the numbers in the factorization. in A: -1*-1 = +1 but in B: +1*-1=-1 and that's not what we're looking for. So A is the correct answer.
