The switching expression corresponding to $$f(A, B, C, D) = \sum (1, 4, 5, 9, 11, 12)$$ is

A

$$BC'D’ + A’C’D + AB'D$$

B

$$ABC’ + ACD + B’C’D$$

C

$$ACD’ + A’BC’ + AC'D’$$

D

$$A’BD + ACD’ + BCD'$$