De Morgan’s laws and equivalence – UGC NET Question

Statements A and B restate De Morgan’s laws, showing how negation distributes over “and” and “or”, C correctly defines logical equivalence in terms of matching truth values and D is true because De Morgan’s laws explicitly connect conjunction, disjunction and negation. Statement E is false since contradictory statements cannot both be true in any possible situation; one must be false whenever the other is true. Hence, the combination A, B, C and D only is correct.

Option A:
Option A is incomplete because, although it lists three true statements, it omits D and thus does not explicitly say that De Morgan’s laws are the ones relating “and”, “or” and “not”. Without D, the named connection between these operators is not emphasised.

Option B:
Option B is also incomplete because it leaves out A and thereby fails to include the first De Morgan equivalence concerning the negation of “p and q”. That omission makes the description of the laws partial.

Option C:
Option C is correct as it bundles all four true statements, fully describing De Morgan’s laws and logical equivalence, while rejecting E, which mischaracterises contradictions. It aligns with the logical tools used in UGC NET reasoning.

Option D:
Option D is wrong because it includes E, the false statement about contradictions, and omits C, the formal definition of logical equivalence. This combination mixes error with omission.