Question

Which of these holds a galaxy together?

A.disk
B.gravity
C.open clusters
D.globular clusters

Answer 1

'Disk', 'open cluster', and 'globular cluster' are shapes into which stars gather themselves.

For holding big groups of stars together, we have to find some kind of force. 'Gravity' does the job nicely. (B)

Answer 2

The answer is B - gravity