What characterizes an exothermic reaction?

An exothermic reaction is characterized by the release of energy, which typically occurs in the form of heat. This means that during the reaction, the system loses energy to its surroundings, resulting in a temperature increase in the surrounding environment. The release of heat is a defining feature of exothermic reactions, and it is why they are often associated with combustion processes, respiration in biological systems, and various chemical reactions that generate warmth.

The other options focus on different aspects of reactions that do not specifically define exothermic processes. For example, while some reactions may require high temperatures to proceed, this is not a characteristic unique to exothermic reactions and does not apply universally. Additionally, the notion that exothermic reactions produce solid products only is also incorrect, as these reactions can yield various products, including gases and liquids. Similarly, absorption of heat from the surroundings is indicative of an endothermic reaction, not an exothermic one.