What is the governing directive for hazardous materials movement by military air?

The correct choice is AFMAN 24-204 because it specifically addresses the requirements and procedures for the movement of hazardous materials by military air. This Air Force Manual outlines the necessary guidelines to ensure safety and compliance with regulations when transporting hazardous materials in aviation operations. It covers aspects such as packaging, labeling, documentation, and handling practices that are crucial for safely moving hazardous goods, thereby minimizing risks during air transit.

The other options do have their respective focuses. AFMAN 25-301 deals more with munitions management; AFMAN 30-130 pertains to logistical support and supply; and AFMAN 31-102 focuses on security and access control policies. These manuals do not specifically address the air transportation of hazardous materials, making them less relevant to the context of the question.