instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
What does Thapar decry as helping to put too much focus on certain aspects of Indian history?, Context: Romila Thapar notes that the division into Hindu-Muslim-British periods of Indian history gives too much weight to "ruling dynasties and foreign invasions", neglecting the social-economic history which often showed a strong continuity. The division into Ancient-Medieval-Modern periods overlooks the fact that the Muslim conquests occurred gradually during which time many things came and went off, while the south was never completely conquered. According to Thapar, a periodisation could also be based on "significant social and economic changes", which are not strictly related to a change of ruling powers.[note 1]
answer:
division into Hindu-Muslim-British periods


question:
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.
answer:
two tones are played simultaneously


question:
How long is the current railroad in American units?, Context: Israel has 18,096 kilometers (11,244 mi) of paved roads, and 2.4 million motor vehicles. The number of motor vehicles per 1,000 persons was 324, relatively low with respect to developed countries. Israel has 5,715 buses on scheduled routes, operated by several carriers, the largest of which is Egged, serving most of the country. Railways stretch across 949 kilometers (590 mi) and are operated solely by government-owned Israel Railways (All figures are for 2008). Following major investments beginning in the early to mid-1990s, the number of train passengers per year has grown from 2.5 million in 1990, to 35 million in 2008; railways are also used to transport 6.8 million tons of cargo, per year.
answer:

590 mi