21. Of the highlighted sentences, select the one that best supports the main idea of the excerpt.

Answer: C

Explanation:

If you want to keep hearing your favorite songs, keep the volume low.

This statement emphasizes the importance of maintaining a lower volume level to preserve hearing, which aligns closely with the main idea of the excerpt regarding sound levels and their impact.

A) Sometimes it even sounds like noises are competing to see which can be loudest.

While this sentence describes a chaotic auditory environment, it does not directly support the main idea about the importance of volume control. Instead, it focuses on the competition of sounds rather than the implications of loudness on hearing.

B) If you're trying to listen to your MP3 player on the school bus, you might be tempted to turn the volume up even louder.

This option highlights a common scenario but does not advocate for volume control. It suggests a reaction to external noise rather than addressing the need to keep the volume low to protect hearing.

C) If you want to keep hearing your favorite songs, keep the volume low.

This statement directly supports the main idea by encouraging the listener to manage volume levels to avoid hearing damage, making it the best choice among the options provided.

D) A school orchestra playing at top volume can easily reach 100 decibels, and some brass and percussion instruments reach 130 to 140 decibels at close range.

Although this sentence provides information about loud sound levels, it does not offer advice or a solution for listening safely. It serves to illustrate the potential danger of high volumes but does not convey the importance of controlling volume for personal enjoyment.

Conclusion

Option C stands out as it directly addresses the necessity of keeping volume levels low to protect hearing and enjoy music, thereby supporting the main idea effectively. In contrast, the other options either describe scenarios or provide information that does not connect to the core message of volume control and its implications on hearing.