Which vessel's navigation rules apply when a vessel is underway but not making way?

When a vessel is underway but not making way, both Inland and International navigation rules apply because the definitions and requirements around not making way are addressed in both sets of rules. A vessel is considered to be "underway" when it is not at anchor, or made fast to the shore, or aground. Being "not making way" refers to a situation where the vessel is in motion but not moving forward through the water, such as when it is drifting.

In both sets of navigation rules, various requirements and protocols still apply to vessels that are considered underway, which includes obligations regarding safe navigation, signaling, and the responsibilities of operators to avoid collisions. Therefore, it is essential to understand that both rule sets are relevant in situations involving vessels that are not actively propelling themselves, leading to the conclusion that the correct answer encompasses both Inland and International navigation rules.