Give an example of how density-dependent and density-independent factors might interact.

It should be cryosphere and hydrosphere

Im assuming this is a multiple choice answer what is the answers to chooce from?

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