Which individual is currently one of Oregon's U.S. Senators?

The correct choice identifies Ron Wyden as one of Oregon's U.S. Senators. He has been serving in this role since 1996. As a senior member of the Senate, Wyden has played a significant role in various legislative efforts, representing the interests of Oregonians at the national level.

In the context of the other individuals listed, Jeff Merkley is also currently a U.S. Senator from Oregon, having been elected in 2008. However, the question specifically asks for one of the current senators, and in this instance, Ron Wyden is indeed one of them. Kate Brown is the former governor of Oregon, which is a state leadership position but does not pertain to the Senate. Ted Kulongoski served as the governor of Oregon from 2003 to 2011, also not relevant to the position of U.S. Senator.

Thus, Ron Wyden's longstanding role in the Senate and advocacy for Oregon's issues solidify why he is recognized in this context.