Spatial ordering is an effective method of organization for ___ essays ... Answer expository. narrative. persuasive. descriptive.

descriptive

Spatial relationships have to do where objects are located (in 3-dimensional space.)

If you were describing, for example, what the interior of a classroom looked like, here's an excerpt:

... the third desk in the second row, the one that's next to the trash can and to the left of the window ...