Answer:
A. potassium nitrate
Explanation:
A change in temperature generally increases the solubility of solutes in solutions.
To solve this typical problem, its best to use the solubility curve which shows the solubility of different compounds in water.
Find the curve attached below;
We can see that with increasing temperature, the solubility of potassium nitrate increases the most with increasing temperature.
The solubility of sodium chloride rarely changes with an increase in temperature.