Final Answer:
Amber is tipped off that Tori is planning to run away from Serenity when she finds a hidden map. The correct option is A.
Step-by-step explanation:
Discovering a hidden map serves as a clear indication that Tori is planning to leave Serenity. The hidden map implies a deliberate attempt to plan and navigate a route, suggesting a purposeful departure. Unlike other options, such as packing a suitcase, overhearing a conversation, or leaving a note, finding a hidden map provides a tangible and direct piece of evidence related to Tori's intentions. The map becomes a significant clue, allowing Amber to discern Tori's plan and potentially intervene or address the situation before Tori departs.
The correct option is A.