Kai is talking to a friend who tells him she just saw a black hole in space. How should he respond?
Tell his friend to verify her sighting through a compound telescope, since many celestial objects look similar to black holes otherwise.
Tell his friend that black holes are too far away for us to view them without a sextant, so it is unlikely she saw a black hole.
Tell his friend that black holes can only be detected from their quasars, and ask her if she saw a quasar, or a glowing ring around a black spot in space.
Tell his friend that this is unlikely as black holes are invisible to the naked eye because their light cannot travel back to us in order for us to view them.