Which chart is referred to for battery duration information for BUS 1?

The correct answer is the Battery Duration Chart - 3 Battery BUS. This chart specifically provides information about the duration of battery life under various load conditions for the 3 Battery BUS system. It helps operators understand how long the batteries will last given specific usage scenarios and load profiles, which is crucial for mission planning and operational readiness.

In a multi-battery setup like this, the duration chart takes into account the additional complexities and settings that arise from using three batteries. The data presented gives insights into factors such as the recharging capabilities, operational limits, and energy consumption rates that are essential for maximizing the effectiveness and reliability of the aircraft's systems during operations.