What is occurring in the diagram below? a. alleles are independently assorting
b. segments of dna are crossing over
c. sister chromatids are separating
d. genes are replicating

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