What Basic Expeditionary Airfield Resources (BEAR) system supports flight operations for a second and subsequent squadron at an austere location?

The option referring to the "Follow-on flightline" is correct because it is specifically designed to support flight operations for additional squadrons deployed to austere locations after the initial establishment of operations. The Follow-on flightline provides the necessary infrastructure and equipment to expand capabilities beyond the initial deployment, allowing multiple squadrons to effectively conduct their missions.

This line is essential in scenarios where air operations grow, as it ensures that all subsequent forces can be accommodated without compromising operational effectiveness. The Follow-on flightline builds upon the resources and systems already in place, allowing for seamless and efficient integration of additional support without requiring a complete re-establishment of flight operations.

In contrast, the other options serve different purposes. The Initial flightline is intended for the first squadron's operations and does not address the needs of additional squadrons. Basic equipment line refers to the equipment and supplies necessary to set up operations but does not specifically relate to flight operations support for follow-on squadrons. The Portable operation base points to a mobile setup that can facilitate operations in various environments, yet it does not specifically tailor to the requirements of multiple squadrons working simultaneously at the same location.