The following sentence is a theorem of truth functional logic. ( P → ( Q → ( P ∧ Q ))) (a) Explain in a sentence how to use a natural deduction proof to show that a sentence of TFL is a theorem (1...

The following sentence is a theorem of truth functional logic.

(P
→ (Q
→ (P
∧
Q)))

(a) Explain in a sentence how to use a natural deduction proof to show that a  sentence of TFL is a theorem (1 point).

(b) Using any of the proof rules (from Ch. 16 & 18 of the text) in the natural  deduction system, complete a proof that shows that this sentence is a theorem