What can be said about endothermic reactions in terms of energy change?

Endothermic reactions are characterized by the absorption of energy from their surroundings, typically in the form of heat. This energy absorption occurs because the total energy of the products is higher than that of the reactants, which means that energy must be supplied for the reaction to proceed. As a result, the surrounding environment often feels cooler as energy is drawn in.

In the context of the choices provided, the correct statement about endothermic reactions highlights this need for energy input, effectively emphasizing that these reactions are dependent on external energy sources to initiate and sustain the reaction process. This property is a fundamental characteristic that distinguishes endothermic reactions from exothermic reactions, which release energy instead.

For additional clarity, while activation energy is essential for all reactions, including endothermic ones, it specifically pertains to the initial energy required to start the reaction rather than characterizing the overall thermodynamic nature of the reaction. Similarly, endothermic reactions do not inherently rely on high temperatures; they can occur at varying temperatures depending on the specific reaction and conditions involved.