Concept:A reaction that absorbs heat energy from its surroundings is called an endothermic reaction.Explanation:The prefix "endo" means to take in or absorb, and "thermic" refers to heat.So, an endothermic process is one in which heat is absorbed.This causes the products to possess more energy than the reactants.Since the given reaction absorbs heat, it is classified as endothermic.Answer:B. endothermic