Simplify each of the following expressions by applying one of the theorems. State the theorem used. (a) X′Y′Z + (X′Y′Z)′ (b) (AB′ + CD)(B′E + CD) (c) ACF + AC′F (d) A(C + D′B) + A′ (e) (A′B + C + D)(A′B + D) (f) (A + BC) + (DE + F )(A + BC)′