How Is the Presence of Space Debris Accounted for by Solar

How is the presence of space debris accounted for by solar system models?

A) Space debris is left over material from the early solar system that never formed into a planet.
B) Space debris was formed by the collision of objects after the planets formed.
C) Space debris is material that existed in our region of space before the sun formed.
D) Both a and b
E) All of the above