What is a significant feature of galaxy clusters?

Galaxy clusters are significant astronomical structures that contain a large number of galaxies, all gravitationally bound together. This mutual gravitational attraction allows galaxies within the cluster to interact with one another in ways that can lead to various phenomena, such as galaxy merging and interactions. The aggregation of these galaxies is a crucial aspect of the formation and evolution of large-scale structures in the universe.

In the context of galaxy clusters, the formation due to mutual gravity highlights the importance of gravitational forces in cosmic structures. As galaxies fall into a cluster, they can be influenced by its potential well, leading to dynamic processes that shape both the galaxies and the overall structure.

The other options do not accurately describe the defining characteristics of galaxy clusters. For example, isolation from other galaxies contradicts the nature of clusters, which are dense regions of the universe. While dark matter does play a significant role in the mass and structure of clusters, it alone does not characterize their formation. Lastly, while supernovae occur within galaxies, they are not a defining feature of galaxy clusters as a whole. Thus, the formation of galaxy clusters through mutual gravity is the most accurate and comprehensive option.