Which of the following lines are part of route pairing 4?

The correct response indicates that the Warminster Line and the Airport Line are part of route pairing 4. This pairing is established based on operational efficiency and scheduling purposes within the SEPTA system. Route pairings ensure that trains operate in a coordinated manner, allowing for more streamlined services and improved connectivity for passengers.

The Warminster and Airport lines both serve distinct yet complementary roles in connecting suburban commuter traffic with key destinations, including the airport. Effective route pairing like this maximizes utilization of train resources and minimizes scheduling conflicts.

Other options detail different line combinations, which do not fall under route pairing 4, as they serve different routes and operational structures within the SEPTA network. Understanding the specific pairings is essential for navigating the transit system effectively and planning efficient travel across various lines.