In the past, many artists worked under the system of patronage. What would you argue is the greatest benefit to an artist of working for a patron? A.
The patron allows artists to create without any guidelines or restraints.

B.
The patron allows artists to concentrate on creating artwork as their main occupation.

C.
The patron allows artists to fully own their work for the rest of their lives.

D.
The patron allows artists the take as long as needed to create a piece of art.

relief sculpture - images are set against a flat background.

a coin is a good example: the inscription, the date, and the figure are slightly raised above a flat surface. the ancient egyptians sometimes carved figures into a flat surface.  

pro: they take significantly less time to make and do not require as much tools or skills as free-standing

cons: not nearly as realistic, as it is not fully 3-d, and does not have the details that a free-standing one does.

freestanding sculptures (also called  carved in the round) are not attached to any  background.   they are 3-dimensional  and fully rendered.