The energies of species in a three-step reaction are listed relative to the reactants: Intermediate 1 at 20 kJ, Intermediate 2 at 15 kJ, and products at −60 kJ. What is the overall enthalpy change, ΔH, for the reaction?
a) −25 kJ
b) +60 kJ
c) −60 kJ
d) −75 kJ