The cluster method (motions of galaxies in a cluster of galaxies) can be used to determine the cluster s mass

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Quizplus · Accepted Answer

The cluster method involves measuring the motions of galaxies within a cluster, which can then be used to determine the total mass of the cluster through calculations based on gravitational attraction. Therefore, the best choice is mass (C). The cluster method uses the gravitational interactions between the galaxies in a cluster to determine the cluster's mass. By observing the motions of the galaxies, astronomers can infer the amount of mass present in the cluster, including both visible matter (stars, gas, dust) and dark matter.

The Cluster Method (Motions of Galaxies in a Cluster of Galaxies)