Which statement is true concerning the evidence for black holes? A. Scientists can see black holes with powerful telescopes. B.Scientists can see the effect of black holes on nearby stars. C. Scientists can see trails left in space by black holes. D.There is no evidence for black holes.
Black holes themselves can not be seen, nor do they leave trails (since emptiness does not have to be caused by a black hole), but there is evidence for black holes: scientists can see the effects of their gravity on nearby stars. The answer is B.