Through which medium will sound travel most rapidly?

The answer is solid. Solid has molecules closely packed together so sound vibrates through these molecules and they can be transmitted most rapidly.

Honestly "global warming" may be a slight possiblity, however they called it "climate change" because its not real, in fact we had one of our coldest days here not too long ago, and the "issues" with this subject is a blindfold for actual problems.