We group them by their style and by their time period
Thomas Edison’s phonograph was the first to successfully record the human voice. His phonograph recorded sound on tinfoil wrapped around a rotating cylinder.
You acquire a Copyright. This is done by registering your song with the U.S. Copyright Office if you live in the U.S.
A is the answer as proportion is the reason why art has spaces and this helps to create detail and make balance art work. it is most commonly found in portraits and negative and positive space drawings.