What principle states that space is free for use by all countries?

The correct answer is the UN Principles of International Space Law. This principle establishes that outer space, including the Moon and other celestial bodies, is free for exploration and use by all countries, aligning with the goal of promoting peaceful cooperation in space activities. The UN's involvement underscores the importance of maintaining outer space as a domain that is accessible to all nations, regardless of their level of economic or technological development. This approach encourages collaborative scientific research and exploration, fostering an environment where shared benefits can be realized by humanity as a whole.

The other options refer to various aspects of space law and policies but do not encapsulate the principle of free use in the same foundational way that the UN Principles of International Space Law do. International Space Law is a broader term that includes several treaties and agreements, while the Global Space Treaty is not an actual treaty recognized in international law, and the Space Security Framework is more focused on national security issues rather than the principle of free access and use.