In the reaction given, the chemical reaction can be re-written as A + B → C + D This implies, A and B are the reactants, while C and D are the products. The energy level of the products (C+D) is higher (50) on the graph than the energy level of the reactants (A+B), (20). The arrow representing the overall enthalpy change (ΔH) points upward, showing a gain in energy, resulting in a positive ΔH value. i.e ΔH\(_{reaction}\) = ΔH\(_{product}\) - ΔH\(_{reactant}\) ΔH\(_{reaction}\) = (C+D) - ( A+B) = 50 - 20 = +30 ΔH\(_{reaction}\) = + ve , hence, it is an endothermic reaction - option B