Why are supermassive black holes believed to be located at the centre of many galaxies?

Question

Quizplus · Accepted Answer

The orbital motion of material near the center of a galaxy is very fast and can only be explained by the presence of a very massive object, such as a supermassive black hole. As a result, many astronomers believe that supermassive black holes are located at the center of galaxies. The rotation curve of the galaxy (A) indicates the presence of dark matter, but it is not directly related to the location of a black hole. The shape of the bulge in spiral galaxies (C) can be supported by a central mass concentration, but it doesn't necessarily mean it is a black hole. The spiral structure (D) does not require a black hole to maintain the spiral arms.

Why Are Supermassive Black Holes Believed to Be Located at the Centre