What is the meaning of 'loud' here?

Hello.

I want to know how to understand the meanig of 'loud' in the next sentence.

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The boy liked rock music, and he liked it loud.

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I guessed lod means 'really'. (a) "He liked rock music real much." Isn't it?

But in a sense, it sounds like (b) "he lked rock music turned on loudly."

What is right,(a) or (b) or any other meaning?