Before the edict of milan, christian art
a. could only be seen in the christian orthodox cathedrals.
b. presented christian stories through multi-leveled symbolism.
c. reflected the strongly spiritual focus of the wealthy leadership.
d. contained images of symbolic christian people who would go unnoticed by pagans

I believe the answer is: D. contained images of symbolic Christian people who would go unnoticed by pagans.

Prior to the edict of milan, The roman government prohibit the exercise of Christian religion in any form including artworks. Because of this, the christian art has to be hidden under the surface. After the edict, the government create a toleration for people who exercise christian religion, so the images of symbolic christian could be made more noticable.