All of the following are important elements to projecting an idea to a concrete work of art, except which?
a. balance
c. metaphor
b. design
d. symmetry

The important elements to create concrete work of art are balance, design and symmetry; so Metaphor is not part of it.

C. metaphor is not needed in projecting and idea

The gregorian chant was a major cultural milestone in the middle ages. it was one of the first codified forms of music meant to be played as written, where previously it was difficult to mass-produce and disseminate any music. what's more, these chants were also some of the first examples of musical notation: the notes and bars of today's music sheets are a reflection of centuries of evolution beginning with these chants. it became official throughout the entirety of the catholic church, meaning that nearly all of europe followed this musical notation and styling.