What is the primary characteristic of the NGC 6240 galaxy?

NGC 6240 is primarily characterized by the presence of two supermassive black holes that are the result of a merger between two smaller galaxies. This phenomenon is significant because the collision and merging process can lead to a variety of astrophysical activities, including the formation of new stars and increased activity around the supermassive black holes. The interaction of these black holes also creates unique features in the galaxy's structure and can influence its evolution over time. In the case of NGC 6240, observations have indicated signs of intense activity associated with the black holes, further cementing its distinction as a galaxy resulting from a collision of galactic cores.

The other options do not accurately reflect the primary characteristics of NGC 6240. While it may have regions of star formation, that aspect is secondary to the more defining characteristic of the dual black holes. Similarly, it does not represent a single, large spiral galaxy but rather a more irregular shape resulting from the merger. Lastly, there is substantial evidence of black holes in NGC 6240, contradicting the idea that it has no black holes at all.