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.)
(T · ~U) ⊃ ~W
~W ⊃ X
~Z ⊃ W
~(X · Z) / T ⊃ U
(A)Valid (B)Invalid. Counterexample when T, X, and Z are true and U and W are false (C)Invalid. Counterexample when T and X are true and U, W, and Z are false (D)Invalid. Counterexample when T, W, and Z are true and U and X are false
A