In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[EX Q]: How was access gained to Alaska, Context: The specifics of Paleo-Indian migration to and throughout the Americas, including the exact dates and routes traveled, provide the subject of ongoing research and discussion. According to archaeological and genetic evidence, North and South America were the last continents in the world with human habitation. During the Wisconsin glaciation, 50–17,000 years ago, falling sea levels allowed people to move across the land bridge of Beringia that joined Siberia to north west North America (Alaska). Alaska was a glacial refugia because it had low snowfall, allowing a small population to exist. The Laurentide Ice Sheet covered most of North America, blocking nomadic inhabitants and confining them to Alaska (East Beringia) for thousands of years.
[EX A]: the land bridge

[EX Q]: How can you reduce the jnd?, Context: The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content. Below 500 Hz, the jnd is about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, the jnd for sine waves is about 0.6% (about 10 cents). The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches. The jnd becomes smaller if the two tones are played simultaneously as the listener is then able to discern beat frequencies. The total number of perceptible pitch steps in the range of human hearing is about 1,400; the total number of notes in the equal-tempered scale, from 16 to 16,000 Hz, is 120.
[EX A]: two tones are played simultaneously

[EX Q]: what is the last subject mentioned?, Context: Some of the county's secondary schools have specialist school status. Some schools have sixth forms and others transfer their sixth formers to colleges. Several schools can trace their origins back many years, such as The Blue School in Wells and Richard Huish College in Taunton. Others have changed their names over the years such as Beechen Cliff School which was started in 1905 as the City of Bath Boys' School and changed to its present name in 1972 when the grammar school was amalgamated with a local secondary modern school, to form a comprehensive school. Many others were established and built since the Second World War. In 2006, 5,900 pupils in Somerset sat GCSE examinations, with 44.5% achieving 5 grades A-C including English and Maths (compared to 45.8% for England).
[EX A]:
Maths