Which of the following ionic equations represents a neutralization reaction?

1. Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
2. H⁺(aq) + OH⁻(aq) → H₂O(l)
3. Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g)
4. Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)