Use indirect truth tables to determine whether the following argument is valid. If the argument is invalid, choose an option which presents a counterexample. (There may be other counterexamples as well.)
P ⊃ (Q ∨ R)
(Q · S) ⊃ ~P
~(~Q ∨ R) / ~P
(A)Valid (B)Invalid. Counterexample when P, Q, R, and S are true (C)Invalid. Counterexample when P and Q are true and R and S are false (D)Invalid. Counterexample when P, R, and S are true and Q is false
C