Question

Two literals are complementary if _____________

(a) They are equal

(b) They are identical and of equal sign

(c) They are identical but of opposite sign

(d) They are unequal but of equal sign

I had been asked this question in a national level competition.

My doubt is from Linguistics in section Introduction to Artificial Intelligence of Artificial Intelligence

Answer 1

Right option is (c) They are identical but of opposite sign

To explain: Two literals are complementary if They are identical but of opposite sign.