Which of these must be documented on the CG-4100S regarding the vessel's master?

The correct answer emphasizes the requirement to document that the master received the SF-95 on the CG-4100S, which is an important form associated with the reporting of claims against the government for damages. This documentation serves as a formal acknowledgment that the master has been made aware of their responsibility regarding potential claims involving the vessel.

In the context of maritime operations, ensuring that the master's awareness of claims procedures is documented is essential for maintaining operational integrity and accountability. The SF-95 is a form used for administrative purposes, and showing that the master received it ensures compliance with regulations concerning loss or damage.

While other aspects like the master's ship history, rank and qualifications, and nationality may be important for operational records or assessments, they do not carry the same necessity for being documented on the CG-4100S. The focus of this form is specific to procedures related to claims, which is why the provision about receipt of the SF-95 takes precedence.