The aspect of of instruments that improved during the Romantic period was the valves. The correct answer is D, valves.
the answer is C
Explanation:
I don't know why I just know that its C because I always choose C for my answers. This is because i'm smart >:)
I believe it was either the Sumerians or the Mesopotamians, hope this helps! :-)
Coming from a violinist it would be taking piano lessons.