Answer: b. The solubility of the liquid will increase
Explanation: If the temperature of the liquids is increased, the solubility of the liquids will increase because the on increasing the temperature, kinetic energy of the particles present in the liquid will increase .
Thus when the kinetic energy increases, the particles would not remain precipitated and thus hereby increasing the solubility of the particles.
The triple point is the point at which the liquid can co-exist in all three forms that is solid, liquid and gas.