Answer
Since the overall reaction is exothermic, we can conclude that energy is being lost to the surroundings; that is, the reaction is releasing energy. We can also say that bonds are being formed.
Work Step by Step
Recall that the term exothermic refers to the loss of heat of a system to its surroundings.
Here, the system is the reaction being studied (A --> B). We are told that this reaction is assumed to be exothermic. That means when this reaction occurs, it is releasing heat to its surroundings (the environment).
Also, typically when bonds are being formed, energy is being released because in making the bonds, the reaction is losing its energy.
Think of it in the reverse way: when you are breaking a bond, it takes energy to break a bond. This means that energy has to be put INTO the reaction (so now the reaction is ABSORBING energy) to break the bond. Similarly, when a bond is being formed, the reaction loses some of its energy in doing so.
