A B C D (a) (b) (c) (d) (e) 0 0 0 0 0 0 0 1 1 0 0 0 1 0 1 1 1 0 0 0 1 0 1 0 1 0 1 0 0 1 1 1 0 1 0 1 0 1 0 0 0 1 0 0 0 0 1 0 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 0 1 1 1 1 1 1 1 0 1 0 0 0 0 1 1 0 0 1 0 0 1 0 1 1 0 0 1 0 1 0 1 1 1 1 0 1 0 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 0 1 1 0 1 1 1 1 0 0 1 1 0 0 1 1 1 1 0 1 1 1 1METHOD: Take a look at the first part of the expression (A.NOT B). All the rows starting A=1 AND B=0 have a 1 in the answer. The answer cannot be (a), (d) or (e) as this is not true for them. Now look at the next part OR C OR D. The answer must have a 1 where C=1 OR D=1 occurs in a row. On the third row, 0010, (b) has a 0 making the answer (c). CHECK all the rest of the rows to see that all conditions are met. They are so answer is (c).
A B X A B X A B X A B X 0 0 1 0 0 0 0 0 0 0 0 1 0 1 0 0 1 1 0 1 1 0 1 0 1 0 1 1 0 1 1 0 0 1 0 0 1 1 0 1 0 0 1 1 1 1 1 1 (a) (b) (c) (d)