Deirdre: Many philosophers have argued that the goal of every individual is to achieve happiness -- that is, the satisfaction derived from fully living up to one' s potential. They have also claimed that happiness is elusive and can be achieved only after years of sustained effort. But these philosophers have been unduly pessimistic, since they have clearly exaggerated the difficulty of being happy. Simply walking along the seashore on a sunny afternoon causes many people to experience feelings of happiness. Which one of the following most accurately describes a reasoning flaw in Deirdre's argument? ['It allows the key term "happiness" to shift in meaning illicitly in the course of the argument.', 'It fails to take into account that what brings someone happiness at one moment may not bring that person happiness at another time.', 'It makes a generalization based on the testimony of a group whose views have not been shown to be representative.', 'It dismisses a claim because of its source rather than because of its content.']