Which type of vessel is not authorized to hold POWs or detainees?

The correct choice indicates that immobilized vessels are not authorized to hold prisoners of war (POWs) or detainees. This is because immobilized vessels lack the capability to operate effectively in a combat or operational environment. Such vessels typically have limited mobility, less control over their operational security, and may not meet the necessary standards for the humane treatment and processing of detainees.

In contrast, operational and sea-going vessels are designed to maintain functionality and security at sea, ensuring that they can manage and protect any detainees according to international law and military regulations. Mobilized vessels, while also able to operate, still possess the necessary qualities for handling POWs due to their readiness for military missions. Therefore, the rationale behind the choice emphasizes that only vessels equipped and capable of safe operation should be entrusted with detention responsibilities.