The relationship between a galaxy and the galaxy cluster of which it is a part is similar to the relationship between a galaxy cluster and the supercluster of which it is a part, with one important difference. What is that difference?
A) Clusters contain only like galaxies (spirals, etc.); superclusters combine clusters of various types.
B) Superclusters rely on copious amounts of dark matter to bind them together; clusters do not.
C) A cluster is a gravitationally bound system; a supercluster is not.
D) The galaxy clusters in a supercluster orbit an enormous black hole; this is not the case with the galaxies in a cluster.

Question

Quizplus · Accepted Answer

A cluster is a gravitationally bound system, meaning that the galaxies within it are held together by gravitational forces. A supercluster, on the other hand, is a larger-scale structure that is not gravitationally bound in the same way; it is more a grouping of clusters that are close in space but not necessarily bound by gravity.

The Relationship Between a Galaxy and the Galaxy Cluster of Which