Final answer:
In the given equation, ΔHf° represents the standard enthalpy of formation, which is the heat involved in forming one mole of a compound from its elements under standard conditions. (option a)
Step-by-step explanation:
In the equation ΔH = sum of ΔHf° products - sum of ΔHf° reactants, ΔHf° represents the standard enthalpy of formation. This is the enthalpy change that occurs when one mole of a compound is formed from its elements under standard conditions, which include a pressure of 1 atm for gases and a concentration of 1 M for species in a solution, with all substances being in their standard states. ΔHf° quantifies the heat absorbed or released during the formation of a compound from its elements.
Hence, the answer is option a