Question: Which Central Appalachian coal producer was responsible for a spill that dumped 306 million gallons of slurry into tributaries of the Tug Fork River?
{'answer': 'Massey Energy', 'supporting_facts': [['Martin County coal slurry spill', 0], ['Martin County coal slurry spill', 1], ['Massey Energy', 0], ['Massey Energy', 1]]}