Final answer:
Ann's mother is displaying an authoritative parenting style, evident by her flexibility in adjusting rules based on circumstances while maintaining overall structure and warmth.
Step-by-step explanation:
Based on the information provided, Ann's mother demonstrates an authoritative parenting style. This is shown by her willingness to set reasonable demands and consistent limits, while also expressing warmth and affection. Additionally, she listens to Ann's point of view and is flexible in making an exception to the rule regarding Ann's curfew, allowing her to stay out late for a special occasion. Authoritative parents are recognized to balance clear rules with understanding and support, ready to discuss and explain the reasons behind their rules and to make exceptions when appropriate.