Sorry if this is posted in the wrong section.

But I came across this question on a test:

Which of the following will evaluate to true only if boolean expressions A, B, and C are all false?

(a) !A && !(B && !C)
(b) !A || !B || !C
(c) !(A || B || C)
(d) !(A && B && C)
(e) !A || !(B || !C)

I think the answer should be "d" but the correct answer seems to be "c" but I don't see why. Can anyone explain this?

Any help is appreciated.

this thread should be in Computer Science Forum any way all these statements are true an the answer is C because if you look at the statement you will find the ! which will invert the answer so the (A||B||C) must result in a false to get the right answer and The rule of Boolean expression OR is that the statement is false if and only if all the of inputs are false where in case of D it is also true for every statement other than A=true , B=true and C=true. :)

I got confused at this, the question is the tricky part, I though it was asking which was true for A = false, B = false and C = false, in which case they are all true (I didn't notice this or I would have got more suspicious). However, its actually asking which is only true when A = false, B = false and C = false... sneaky