A power-driven vessel crossing a river on the Western Rivers has the right of way over __________.

In the context of the navigational rules specific to the Western Rivers, the correct understanding is that a power-driven vessel generally does not have an absolute right of way over any other category of vessels listed. According to the applicable regulations and conventions, the rules of the road prioritize certain circumstances and types of vessels for safe navigation and traffic management.

On the Western Rivers, the concept of "right of way" varies depending on the situation and the specific interactions between vessels. For example, a power-driven vessel may be constrained in its navigation by the river's width, depth, or the presence of other vessels. In these circumstances, the actions of a power-driven vessel must align with the International Regulations for Preventing Collisions at Sea (COLREGS) and may also consider local regulations or guidelines specific to that water body.

While there might be assumptions about the right of way based on vessel type, the reality is that all vessels have to follow the principles of safe navigation, considering their maneuverability and operational limitations. This is why "none of the answers" is the most fitting choice; the relationship between different types of vessels and their rights of way is not so straightforward as to grant one category an absolute priority over another.