Task: Question Generation
Input (English): Galicia is poetically known as the "country of the thousand rivers" ("o país dos mil ríos"). The largest and most important of these rivers is the Minho, known as O Pai Miño (Father Minho), 307.5 km (191.1 mi) long and discharging 419 m3 (548 cu yd) per second, with its affluent the Sil, which has created a spectacular canyon. Most of the rivers in the inland are tributaries of this fluvial system, which drains some 17,027 km2 (6,574 sq mi). Other rivers run directly into the Atlantic Ocean as Lérez or the Cantabrian Sea, most of them having short courses. Only the Navia, Ulla, Tambre, and Limia have courses longer than 100 km (62 mi).
Output (English): What is its longest river?