Lecture 3 (Logic) Common Tautologies and Indirect Proof

Which equivalence is De Morgan's law for negating a conjunction?

1. A.¬(α ∧ β) ≡ ¬α ∧ ¬β
2. B.¬(α ∧ β) ≡ ¬α ∨ ¬β
3. C.¬(α ∧ β) ≡ α ∨ ¬β
4. D.¬(α ∧ β) ≡ ¬α → ¬β