Answer:
a
Step-by-step explanation:
x3+2x2-19x-20
x3+x2+x2+x-20x-20
x2(x+1)+x(x+1)-20(x+1)
(x2+x-20)(x+1)
(x2+5x-4x-20)(x+1)
(x(x+5)-4(x+5))(x+1)
(x-4)(x+5)(x+1)
