Riddle

I have 24 keys but cannot open any locks. Sometimes loud, sometimes soft. What am I?

Choose an answer

A.Chess
B.Piano
C.Mathematics
D.Music
Hint: It's a word with 5 letters, starting with "M".

Answer

Music

Why this is the answer

The "keys" most literally belong to an instrument like a piano or music box, but the source's stated answer is "music" itself, which can indeed sound loud or soft.

This riddle is filed under "What Am I?" Riddles and rated Hard.