In twentieth-century music

a. string players are sometimes called on to use the wood instead of the hair on their bows
b. dissonance has been emancipated
c. percussion instruments have become very prominent and numerous
d. all answers are correct.

The correct answer is D) All answers are correct.

Explanation:

In twentieth-century music it is not uncommon that string players use the wooden part of the bow to create a certain sound effect. Also an emancipation of dissonant sounds has taken place. The twelve-tone technique is one of the first examples of this emancipation. The use of percussion instruments often plays an important role in twentieth-century music. In many cases, pieces are written for instruments that are not typically used in classical musci such as african or latin american instruments.

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