Question: The St. Louis, San Francisco and Texas Railway (SLSF), was a subsidiary railway to the St. Louis-San Francisco Railway, in 1980 it merged into which United States-based railroad company formed from a merger of four major U.S. railroads?
{'answer': 'Burlington Northern Railroad', 'supporting_facts': [['St. Louis, San Francisco and Texas Railway', 2], ['Burlington Northern Railroad', 0]]}