Answer:
Graph 2
Explanation:
Since the energy is on the right side / product side of the equation, we know that this is exothermic. Exothermic reactions are those where the energy level decreases because energy is released into the system. This means that the products on an enthalpy diagram are going to be lower than the reactants.
Here, C is the product and A + B are the reactants, so look for a graph where C is lower and A + B are higher. 2 and 3 fit the description. However, remember that the reactants are always before the products, so only graph 2 works.
Hope this helps!