Combine your understanding of solubility and K_sp to explain why gypsum (CaSO₄·2H₂O) is more soluble in acidic solutions.

• A. Acidic solutions decrease the temperature, decreasing K_sp and solubility.
• B. Acidic solutions increase the temperature, increasing K_sp and solubility.
• C. Acidic solutions increase the concentration of H⁺ ions, which react with sulfate ions, increasing solubility.
• D. Acidic solutions decrease the concentration of H⁺ ions, which react with sulfate ions, decreasing solubility.

Answer: (C)