Arrows in the Energy Diagram Below Represent Enthalpy Changes Occurring

Multiple Choice

Arrows in the energy diagram below represent enthalpy changes occurring in the exothermic formation of a solution:
ΔH_soln = enthalpy of solution
ΔHsolute-solute = enthalpy change involving solute-solute interactions
ΔHsolute-solvent = enthalpy change involving solute-solvent interactions
ΔHsolvent-solvent = enthalpy change involving solvent-solvent interactions
-Which arrow represents ΔH_{solute-solvent}?

A) arrow (a)
B) arrow (b)
C) arrow (c)
D) arrow (d)