All actions are motivated by self-interest, since any action that is apparently altruistic can be described in terms of self-interest. For example, helping someone can be described in terms of self-interest: the motivation is hope for a reward or other personal benefit to be bestowed as a result of the helping action. Which one of the following most accurately describes an error in the argument's reasoning? ['The argument takes evidence showing merely that its conclusion could be true to constitute evidence showing that the conclusion is in fact true.', 'The argument depends for its appeal only on the emotional content of the example cited.', 'The argument does not explain what is meant by "reward" and "personal benefit. "', 'The term "self-interest" is allowed to shift in meaning over the course of the argument.']