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: The Bell Telephone Company was created in 1877, and by 1886, more than 150,000 people in the U.S. owned telephones. Bell Company engineers made numerous other improvements to the telephone, which emerged as one of the most successful products ever. In 1879, the Bell company acquired Edison's patents for the carbon microphone from Western Union. This made the telephone practical for longer distances, and it was no longer necessary to shout to be heard at the receiving telephone. Question: What addition let people stop yelling into the telephone?
answer:
carbon microphone


question:
Passage: After years of negotiation, three Great Powers, Russia, the United Kingdom and France, decided to intervene in the conflict and each nation sent a navy to Greece. Following news that combined Ottoman–Egyptian fleets were going to attack the Greek island of Hydra, the allied fleet intercepted the Ottoman–Egyptian fleet at Navarino. After a week-long standoff, a battle began which resulted in the destruction of the Ottoman–Egyptian fleet. A French expeditionary force was dispatched to supervise the evacuation of the Egyptian army from the Peloponnese, while the Greeks proceeded to the captured part of Central Greece by 1828. As a result of years of negotiation, the nascent Greek state was finally recognized under the London Protocol in 1830. Question: What three countries sent their Navy to Greece?
answer:
Russia, the United Kingdom and France


question:
Passage: From September 1823 to 1826 Chopin attended the Warsaw Lyceum, where he received organ lessons from the Czech musician Wilhelm Würfel during his first year. In the autumn of 1826 he began a three-year course under the Silesian composer Józef Elsner at the Warsaw Conservatory, studying music theory, figured bass and composition.[n 3] Throughout this period he continued to compose and to give recitals in concerts and salons in Warsaw. He was engaged by the inventors of a mechanical organ, the "eolomelodicon", and on this instrument in May 1825 he performed his own improvisation and part of a concerto by Moscheles. The success of this concert led to an invitation to give a similar recital on the instrument before Tsar Alexander I, who was visiting Warsaw; the Tsar presented him with a diamond ring. At a subsequent eolomelodicon concert on 10 June 1825, Chopin performed his Rondo Op. 1. This was the first of his works to be commercially published and earned him his first mention in the foreign press, when the Leipzig Allgemeine Musikalische Zeitung praised his "wealth of musical ideas". Question: What instrument did Chopin play in front of Tsar Alexander I?
answer:

eolomelodicon