Which of the following best describes an exothermal reaction?

An exothermal reaction is characterized by the release of heat during the chemical process. In such reactions, the system undergoing the reaction gives off energy in the form of heat to the surroundings. This results in an increase in temperature of the surrounding environment. This is a fundamental characteristic of exothermal reactions, which can be observed in various processes, such as combustion or respiration, where energy is transferred out of the reacting substances and into their surroundings.

In contrast to options that describe endothermic processes or reactions that do not involve temperature changes related to heat transfer, the identification of an exothermal reaction specifically points to its nature of releasing heat, making it the most accurate description of the phenomenon.