Answer:
To reduce her dissonance, Rosie is changing a problem cognition to make it more consonant with her behavior.
Step-by-step explanation:
Social psychology tries to find and explanation of relevant factors that affect people's behavior. In the case given, Rosie tries to justify her lack of interest in a balanced-well-established food diet by saying "Live fast, die young". She accepts that phrase as true in order to excuse the idea that eating junk food is not bad at all for her.