Define the term monogram. why are they used by artists?

a motif can be 2 or more letters, like someones initials or signature, usually interwoven or otherwise combined in a decorative design, used as a logo or any other source to identify a personal possession. 
they use it sign their work so that people know who painted the piece

The answer is a : varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.hope this : )

For #1 i believe the answer would be d. because it is hard to perfect thatfor #3 i believe the answer would be b. because latin root meaning round  for #6 i believe the answer would be a. because it is a jewish thing