Question: What part of the Assabet River National Wildlife Refuge was formerly used as a dumping ground by the Natick Laboratories until the 1980s?
Sentence (from "Yukon Flats National Wildlife Refuge"): It is the third-largest National Wildlife Refuge in the United States, although it is less than one-half the size of either of the two largest, the Arctic National Wildlife Refuge, or the Yukon Delta National Wildlife Refuge.
Relevant evidence: No