Which of the following phenomena confirms that the universe is not static but expanding?

Consider the following statements with reference to dark matter: I. It is presently understood to consist of ordinary baryonic matter made up of protons and neutrons. II. Its presence is inferred from gravitational effects on visible matter and large-scale cosmic structures. III. It does not interact with electromagnetic radiation in the same manner as ordinary matter. Which of the statements given above are correct?

Which large-scale cosmic structure—spanning approximately 50 million light-years and traced by at least 14 galaxies—has been identified as one of the universe's largest spinning formations?