[Olympiad] The solubility of BaSO₄ is 1.05 × 10⁻⁵ mol/L. Calculate its solubility product (Ksp).

1. 1.10 × 10⁻¹⁰
2. 1.05 × 10⁻¹⁰
3. 2.10 × 10⁻⁵
4. 1.10 × 10⁻⁵