Which factor can cause secondary succession? clear cutting
glacial melting
competition
predation

The answers is clear cutting !

Orbit is represented by the blank space

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