阅读下列短文，从每小题的三个选项中选出最佳选项。

Long long ago, people in the Noise Kingdom liked making noise. They did everything loudly. Everyone was a noisy neighbor. The king's birthday was coming. He wanted to hear the loudest noise in the world. So he asked all the people to shout together at twelve o'clock on his birthday! But a child said to his parents, "Let's just open our mouths and listen." All the people heard about this idea. At twelve o'clock on the king's birthday, all the people just opened their mouths and listened. They heard the sounds of the birds and the river. The king said, "What nice sounds!" After that, the Noise Kingdom became quiet. People did everything quietly.