Nitrogen-fixing bacteria live in in protective nodules (bumps) on the roots of some plants. a. mutualism. b. predation. c. commensalism. d. parasitism.

Nitrogen fixing bacteria live in protective nodules on the roots of some plants is Mutualism.

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