Which is better, soundproofing, or sound absorption? and why?

It depends on what you're using it for. Simply because they are different. Soundproofing blocks out the sound, while sound absorption is where the sound is absorbed into something, such as cork.

So, If you are looking to block out sound, soundproofing. If you are looking for something, such as a movie room or music studio, try sound absorption.

it is c) 24hrs

hope i !

i dont know, i dont live in japan sorry though