Suppose a,b denote the distinct real roots of the quadratic polynomial x2+20x−2020, and c,d denote the distinct complex roots of the quadratic polynomial x2−20x+2020. Then the value of ac(a−c)+ad(a−d)+bc(b−c)+bd(b−d) is
(A) 0
(B) 8000
(C) 8080
(D) 16000