Problem: Given the question: Question: "Where did these hunters get their calories from?"  Context: "Evidence suggests big-game hunter gatherers crossed the Bering Strait from Asia (Eurasia) into North America over a land bridge (Beringia), that existed between 47,000–14,000 years ago. Around 18,500-15,500 years ago, these hunter-gatherers are believed to have followed herds of now-extinct Pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific coast to South America."  Answer:
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The answer is:
big-game


Problem: Given the question: Question: "__ has been a central part of agriculture for 5000 years."  Context: "The Alps provide lowland Europe with drinking water, irrigation, and hydroelectric power. Although the area is only about 11 percent of the surface area of Europe, the Alps provide up to 90 percent of water to lowland Europe, particularly to arid areas and during the summer months. Cities such as Milan depend on 80 percent of water from Alpine runoff. Water from the rivers is used in over 500 hydroelectricity power plants, generating as much as 2900 kilowatts of electricity."  Answer:
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The answer is:
irrigation


Problem: Given the question: Question: "__  have strong bills for drilling and drumming on trees"  Context: "Incubation, which optimises temperature for chick development, usually begins after the last egg has been laid. In monogamous species incubation duties are often shared, whereas in polygamous species one parent is wholly responsible for incubation. Warmth from parents passes to the eggs through brood patches, areas of bare skin on the abdomen or breast of the incubating birds. Incubation can be an energetically demanding process; adult albatrosses, for instance, lose as much as 83 grams (2.9 oz) of body weight per day of incubation. The warmth for the incubation of the eggs of megapodes comes from the sun, decaying vegetation or volcanic sources. Incubation periods range from 10 days (in woodpeckers, cuckoos and passerine birds) to over 80 days (in albatrosses and kiwis)."  Answer:
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The answer is:
woodpeckers