Which of the following statements best describes dark matter?

The statement that dark matter exists to account for missing mass in galaxies captures the essence of dark matter’s scientific role in cosmology. Observations of galaxy rotation curves indicate that the visible mass of galaxies—comprised of stars and gas—does not account for the gravitational forces required to hold them together. This discrepancy suggests there is additional mass that is not emitting or reflecting enough electromagnetic radiation to be seen directly, which is where dark matter comes into play.

Dark matter is theorized to make up a significant portion of the total mass in the universe, helping to explain phenomena such as the rotation speeds of galaxies, gravitational lensing, and the large-scale structure of the cosmos. Its existence provides crucial insight into the behavior of galaxies and aids in the formation of our current understanding of universal structure.