Question

If p, q, r are simple propositions, then $(p \land q) \land (q \land r)$ is true then

• A. p, q, r are all false
• B. p, q, r are all true
• C. p, q are true and r is false
• D. p is true and q and r are false

Answer 1

Answer: (B)

p, q, r are all true

Answer 2

$(p \land q) \land (q \land r)$ is true means $p \land q$, $q \land r$ are both true. ⇒ p, q, r are all true.