question: Melting ice is drastically impacting the number of what at glacier national park?
distractor3: icebergs
distractor1: gaisers
distractor2: trees
correct_answer: active glaciers
support: In Glacier National Park ( Figure below ), many glaciers have become ice sheets. In 1850, the park had 150 glaciers. There are only about 25 today. The reason that there is so much melting is that summer temperatures have risen. Scientists estimate that the park will have no active glaciers as early as 2020.