It would be wonderful to observe a singularity (an
infinitely dense concentration of matter) and
obtain direct evidence of the undoubtedly bizarre
phenomena that occur near one. Unfortunately, in
most cases a distant observer cannot see the
singularity; outgoing light rays are dragged back by
gravity so forcefully that even if they could start out
within a few kilometers of the singularity, they would end
up in the singularity itself.
Which of the following sentences would most probably follow the last sentence of the passage?
答案：B