Step 1: Among the four named laws, three deal with gas behavior (pressure, volume, temperature relationships) or solution vapor pressure, while only one deals with heat changes in chemical reactions.
Step 2: Hess's law specifically states that enthalpy change for an overall reaction equals the sum of enthalpy changes of its individual steps, because enthalpy depends only on initial and final states, not on the path taken.
Step 3: This state-function property is exactly what makes Hess's law the one connected to enthalpy, ruling out Gay-Lussac's, Boyle's and Raoult's laws, which concern gas laws and colligative properties instead.
The correct answer is Hess's law.