Which products result in a sum or difference of cubes? check all that apply.

a=(x – 4)(x2 + 4x – 16)
b=(x – 1)(x2 – x + 1)
c=(x – 1)(x2 + x + 1)
d=(x + 1)( + x – 1)
e=(x + 4)(x2 – 4x + 16)
f=(x + 4)(x2 + 4x + 16)

sum of cubes:
(a + b)(a2 – ab + b2) = a3 + b3
difference of cubes:
(a – b)(a2 + ab + b2) = a3 – b3