Barium Hydroxide Is Slightly Soluble in Water,with a K_sp of 5.00

Multiple Choice

Barium hydroxide is slightly soluble in water,with a K_sp of 5.00 × 10^-4 at 298K.The dissolution of barium hydroxide in water is an endothermic process. Ba⁺² (aq) + 2OH^- (aq)
Which of the following will increase the solubility?

A) Barium hydroxide is added to the solution.
B) Sodium hydroxide (NaOH) is added to the solution.
C) The temperature is decreased.
D) HCl is added to the mixture.(HCl reacts with OH-,removing it from the system. )