Show that each of the following arguments is invalid by providing a counterexample — that...

Show that each of the following arguments is invalid by providing a counterexample — that is, an assignment of truth values for the given primitive statements p, q, r, and s such that all premises are true (have the truth value 1) while the conclusion is false (has the truth value 0).

a) [(p ˄ q) ˄ [p → (q → r)]] → ¬r

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b) [[(p ˄ q) → r] ˄ (¬q ˅ r)] → p

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c)

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d)