A、They were formed alter stars died. B、They were formed after two stars collided. C、They were formed after stars lost gravity. D

(3)You learn in science that black holes formed when stars collapsed and that they have such incredibly intense gravity that not even light can escape them, at least that’s the theory. Black holes are some of the strangest and most mysterious object in space. NASA says two of its space telescopes have found new information about an odd repeating light signal coming from the center of a distant galaxy in the Virgo constellation , about 3. 5 billion light years from Earth. Scientists were able to track the changing light patterns over the past 20 veal’s, using ultraviolet data from Hubble and the Galaxy Evolution Explorer.(4)The two black holes are expected to collide and merge in less than a million years, triggering a huge explosion. Black holes are a huge mystery. Scientists think there are billions of them in the universe. But they can’t actually see them.
3. How did black holes come into being?
4. What is the outcome of two black holes colliding?