HELP ME UNDERSTAND HOW TO DO THIS BCUZ ITS DUE TONIGHT AS IN NOOOW!!!

o(≧口≦)o

The art of using and understanding space involves 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.