The correct sequence of the sea ports connecting the western part of United States (USA) to Western Europe is as follows:
- San Francisco (III): Located on the west coast of the United States, it is the starting point for many routes to Europe.
- Honolulu (I): Situated in the Pacific, it is an important stop for international shipping between the USA and Asia/Europe.
- Colon (IV): Located at the Caribbean entrance to the Panama Canal, Colon is a key port for shipping to and from the USA and Europe.
- London (II): The final destination, located in Western Europe, completes the connection. Thus, the correct option is (D).