Rin Corbett works at a software company and is in charge of the help desk. A short while ago, she received a call from a discontented customer about a problem he is facing due to the company's software. Though she tried to help the customer with the software, he refused to listen to her. He continued yelling at her and finally banged the phone down. Corbett feels exasperated after hanging up the phone and goes for a cup of coffee to calm herself down. What makes Corbett's anger an emotion, rather than a mood?