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.