Exothermic reactions are those in which heat/energy is released during the formation of the product.
Due to release of energy, the following equation is always followed: Energyproduct<Energyreactants
In the given graphs, H represents energy. According to each graph:
In graph A:Energyproduct<Energyreactants is followed.
In graph B:Energyproduct >Energyreactants
In graph C and D:Energyproduct=Energyreactants