The correct answer is option 1. Latent heat corresponds to the change in heat at constant temperature only.
Latent heat refers to the heat energy that is either absorbed or released during a phase change of a substance, such as the transition from a solid to a liquid or a liquid to a gas. During these phase changes, the temperature of the substance remains constant.
Option 2 (volume only) is incorrect because the volume of the substance does not play a direct role in the measurement of latent heat.
Option 3 (pressure only) is also incorrect because like volume, pressure does not directly affect the measurement of latent heat.
Option 4 (temperature, volume, and pressure) is incorrect because latent heat specifically refers to changes in heat at constant temperature, and it is independent of volume and pressure changes.
In conclusion, latent heat is associated with the change in heat at constant temperature only.