In Which of These Cases Does Gravity, a Long-Range Force

Multiple Choice

In which of these cases does gravity, a long-range force, NOT result in a bound system?

A) orbital movements of globular clusters about the center of the Milky Way
B) disruption by tidal forces from the Milky Way of the most recently discovered member of the Local Group, Canis Major Dwarf, a close companion of the Milky Way Galaxy
C) motions of galaxies within clusters
D) motions of clusters within superclusters