Which part of the proof does the fourth statement and reason represent

Consider the polynomials given below. p(x) = x4 + 3x3 + 2x2 – x + 2 q(x) = (x3 + 2x2 + 3)(x2 – 2) determine the operation that results in the simplified expression below. 35 + x4 – 573 - 3x2 + x - 8 a. p+q b. pq c.q-p d. p-q