The Oort Cloud of Comets Surrounding the Solar System at a Distance

The Oort cloud of comets surrounding the solar system at a distance of about 50,000 au is believed to be

A) material flung outward by the gravity of the newly formed giant planets early in the history of the solar system.
B) an interstellar cloud through which the Sun and planets happen to be passing but is not otherwise connected to the solar system.
C) debris left behind at that distance by the collapse of the interstellar cloud that formed the Sun and planets.
D) material captured from interstellar space by the Sun's gravity.