In thermodynamics, the sign of the enthalpy change ($\Delta H$) determines whether a process absorbs or releases energy.

1. Heat Absorption (Endothermic): Processes that absorb heat from the surroundings have a positive enthalpy change ($\Delta H > 0$) .
2. Heat Evolution (Exothermic): Processes that release heat to the surroundings have a negative enthalpy change ($\Delta H < 0$) .
3. Enthalpy of Solution ($\Delta_{sol}H$): This is defined as the enthalpy change when one mole of a substance dissolves in a specified amount of solvent . For most ionic compounds, the dissolution process is endothermic .

Comparing the given heat of solution values:

• $HNO_{3}$ ($\Delta H = -33$): Exothermic; releases heat.
• $KCl$ ($\Delta H = +17.64$): Endothermic; absorbs heat.
• $NH_{4}NO_{3}$ ($\Delta H = +25.5$): Endothermic; absorbs heat.
• $HCl$ ($\Delta H = -74.1$): Exothermic; releases heat.

Since the question asks for the maximum quantity of heat absorbed, we look for the highest positive value. $NH_{4}NO_{3}$ absorbs $25.5$ kJ of heat per mole, which is greater than the heat absorbed by $KCl$ ($17.64$ kJ/mol). Therefore, Option C is correct.