Final answer:
The self-ionization of water is an endothermic process that requires energy to break the bonds within the water molecules and form H+ and OH- ions. The correct option is a) Endothermic.
Step-by-step explanation:
The self-ionization of water is an endothermic process. This means that energy is required to break the bonds within the water molecules and form separate H+ and OH- ions.
The energy needed to break these bonds is typically provided by the surrounding environment, such as heat. The reaction can be represented by the equation: H₂O(l) <--> H+(aq) + OH-(aq).