Correct Option: C

The fundamental reason for the bonding of atoms is that they lose their stored potential energy by forming bonds. This is the only reason for chemical combination. So, when a bond is formed between two atoms, stored potential energy is always released to the surroundings. However, according to the Law of Conservation of Energy, a bond cannot form unless this bond energy is transferred from the interacting atoms to the rest of the system. So overall the energy of the system remains the same.