Final answer:
Exothermic reactions are spontaneous under normal and standard conditions as they release energy in the form of heat.
Step-by-step explanation:
Under normal and standard conditions, a spontaneous reaction is one that occurs without the need for external energy to be added. This means that the reaction will happen on its own, releasing energy. In the context of the given options, the correct answer would be Exothermic because exothermic reactions release energy in the form of heat.