Question

The number of values of r ∈ {p, q, ~ p, ~ q} for which ((p∧q) ⇒ (rvq)) ∧ ((p∧r) ⇒ q) is a tautology, is

(1) 3

(2) 2

(3) 1

(4) 4

Answer 1

Correct option is (2) 2

For this to be tautology, (~pv ~ r v q) must be always true which follows for r = ~p or r = q.