Tautology, contradiction and contingency – UGC NET Question

Statements A, B and C provide the standard classification of formulas into tautology, contradiction and contingency. Statement E is also true because truth tables are a systematic way to test which of these categories a formula falls into. Statement D is false because the existence of contingencies means there is indeed a third kind of formula. Therefore, A, B, C and E only make up the correct set.

Option A:
Option A is incomplete as it omits E and thus does not mention the main procedural tool, the truth table, which is central to exam questions on this topic.

Option B:
Option B is wrong since it includes D, which denies the existence of contingencies, contradicting statement C.

Option C:
Option C is correct because it captures all true statements and excludes D, which misclassifies propositional forms.

Option D:
Option D is incorrect as it retains D and omits A, losing the definition of tautology while including a false generalisation about all formulas.