What document underscores the master's responsibility for maintaining stability conditions?

The Stability Booklet is the correct choice, as it is a vital document that outlines the vessel's stability criteria and guidelines. This booklet provides essential information regarding the ship's design, stability calculations, and operational limits, which the master must understand and adhere to in order to maintain the safety and stability of the vessel during operations. It emphasizes the master's responsibility to ensure that the vessel remains within safe stability parameters while loading, unloading, and operating.

In contrast, a Weather Report provides information on current and forecasted weather conditions but does not specifically address the stability of the vessel. The Safety Manual contains general safety procedures and protocols but does not focus exclusively on stability responsibilities. A Cargo Manifest is a list of the cargo on board, which is important for operational purposes, but it does not directly address how to maintain stability. Therefore, the Stability Booklet is integral for the master to fulfill their responsibilities regarding vessel stability.