The art of using and understanding space involves

D. All of above

*If these were options for your question, D indeed is the answer*

A. varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.

B. showing a change from light to dark in an object by darkening areas that would have a shadow.

C. placing part of one shape or form in front of another.

D. all of the above.

the commander in chief

the spanish  

hope this meaning spain btw