A student places \(10.0\text{ g}\) of solid ammonium nitrate, \(\text{NH}_4\text{NO}_3(s)\), into \(100.0\text{ g}\) of distilled water at \(22.0\ ^\circ\text{C}\) inside a well-insulated coffee-cup calorimeter. The mixture is stirred until the solid completely dissolves, and the final temperature of the solution is recorded as \(15.5\ ^\circ\text{C}\). Assuming negligible heat exchange with the calorimeter walls and the air, which of the following correctly classifies the dissolution process and describes the transfer of thermal energy?