Which of the following items is essential for documenting activities at a mobilization center?

The essential item for documenting activities at a mobilization center is the T-card. A T-card system is commonly used in incident management as it helps to effectively track resources, personnel, and status of operations in a visual and organized manner. Each card can represent an individual resource or team, allowing for quick assessments of what assets are available, currently deployed, or in need of attention. This is particularly important in a mobilization center where communication and resource allocation are critical during emergencies.

While GPS tracking, patient care reports, and incident summary reports serve important roles in emergency management and patient care documentation, they do not specifically cater to the day-to-day operational tracking that a T-card system provides. GPS tracking primarily focuses on location data, patient care reports document the specifics of individual patient interactions, and incident summary reports synthesize information after an incident has concluded, rather than during active mobilization efforts. Thus, the T-card stands out as the most appropriate and essential tool for real-time documentation and management in a mobilization center context.