Final answer:
Ann likely suffers from Antisocial Personality Disorder, indicated by her lack of remorse, egocentric behavior, and impulsive actions.
Step-by-step explanation:
Based on the description provided, Ann most likely has Antisocial Personality Disorder (APD). Individuals with Antisocial Personality Disorder often display a lack of regard for the rights of others, engage in deceitful or manipulative behavior, may act impulsively, and have difficulty feeling remorse or guilt for their actions.
Ann's lack of guilt for committing murder and absence of sympathy for the victim's family are characteristic of APD. Additionally, her impulsive decision to murder the class president after losing the election further supports this diagnosis, as individuals with APD often engage in rash or reckless behaviors without considering the consequences.