When two plates form a subduction zone, which plate will subduct?
A. The continental plate
B. The less dense plate
C. The denser plate
D. Both plates are equally likely to subduct.

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it