instruction:
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
question:
Passage: 1,500 V DC is used in the Netherlands, Japan, Republic Of Indonesia, Hong Kong (parts), Republic of Ireland, Australia (parts), India (around the Mumbai area alone, has been converted to 25 kV AC like the rest of India), France (also using 25 kV 50 Hz AC), New Zealand (Wellington) and the United States (Chicago area on the Metra Electric district and the South Shore Line interurban line). In Slovakia, there are two narrow-gauge lines in the High Tatras (one a cog railway). In Portugal, it is used in the Cascais Line and in Denmark on the suburban S-train system. Question: How many narrow-gauge lines in Slovakia?
answer:
two


question:
Passage: Brass instruments in the Renaissance were traditionally played by professionals who were members of Guilds and they included the slide trumpet, the wooden cornet, the valveless trumpet and the sackbut. Stringed instruments included the viol, the harp-like lyre, the hurdy-gurdy, the cittern and the lute. Keyboard instruments with strings included the harpsichord and the virginal. Percussion instruments include the triangle, the Jew's harp, the tambourine, the bells, the rumble-pot, and various kinds of drums. Woodwind instruments included the double reed shawm, the reed pipe, the bagpipe, the transverse flute and the recorder. Question: Brass instruments were traditionally played by profession guild members during what era?
answer:
the Renaissance


question:
Passage: In 1880, Bell received the Volta Prize with a purse of 50,000 francs (approximately US$250,000 in today's dollars) for the invention of the telephone from the Académie française, representing the French government. Among the luminaries who judged were Victor Hugo and Alexandre Dumas. The Volta Prize was conceived by Napoleon Bonaparte in 1801, and named in honor of Alessandro Volta, with Bell receiving the third grand prize in its history. Since Bell was becoming increasingly affluent, he used his prize money to create endowment funds (the 'Volta Fund') and institutions in and around the United States capital of Washington, D.C.. These included the prestigious 'Volta Laboratory Association' (1880), also known as the Volta Laboratory and as the 'Alexander Graham Bell Laboratory', and which eventually led to the Volta Bureau (1887) as a center for studies on deafness which is still in operation in Georgetown, Washington, D.C. The Volta Laboratory became an experimental facility devoted to scientific discovery, and the very next year it improved Edison's phonograph by substituting wax for tinfoil as the recording medium and incising the recording rather than indenting it, key upgrades that Edison himself later adopted. The laboratory was also the site where he and his associate invented his "proudest achievement", "the photophone", the "optical telephone" which presaged fibre optical telecommunications, while the Volta Bureau would later evolve into the Alexander Graham Bell Association for the Deaf and Hard of Hearing (the AG Bell), a leading center for the research and pedagogy of deafness. Question: The Volta lab improved the phonograph by replacing tinfoil with what substance?
answer:

wax