During the early nineteenth century, the demand for ever-louder sound led to ever-increasing tension on piano strings, making evident the need for stronger framing. Sooner or later, long after factories had taken over the manufacture of other commodities, the Industrial Revolution nevertheless shaped the attitudes of those who decided whether to accept this innovation. To build pianos with steam-powered tools was one thing, to put a cast-iron frame at the center of the instrument, making the product itself a modern factory of sound rather than a fully handcrafted artwork, in wood, was quite another. The resulting debate was vigorous, with many feeling certain that iron in the piano would ruin the tone.
--모두 고르시오--
Which of the following statements about the development of the piano can be inferred from the passage? 답: A,C