At which street should a passenger transfer to switch from downtown local to uptown local without extra fare?

The right answer is significant because it aligns with the operational protocols of the transit system regarding fare transfers. In many transit systems, certain transfer points are designated as locations where passengers can change lines without incurring an additional fare. These locations are typically positioned at major intersections or transfer hubs where local trains serve different directions, making it convenient for passengers to switch lines seamlessly.

In this case, the choice of 16th Street as the transfer point between downtown local and uptown local indicates that this street serves as a designated fare transfer location. This allows passengers to switch trains without needing to pay an extra fare, promoting efficient travel between local services. Understanding the specific streets and transfer points relevant to the system can enhance a passenger's experience by facilitating smoother transitions while adhering to fare regulations. Each of the other streets listed likely does not serve as a designated fare transfer point for this train line setup, necessitating an additional fare for transfers at those locations.