Question ID:PT60 S3 Q10 Passage:A ring of gas emitting X-rays flickering 450 times per second has been observed in a stable orbit around a black hole. In light of certain widely accepted physical theories, that rate of flickering can best be explained if the ring of gas has a radius of 49 kilometers. But the gas ring could not maintain an orbit so close to a black hole unless the black hole was spinning. Stem:The statements above, if true, most strongly support which one of the following, assuming that the widely accepted physical theories referred to above are correct? Correct Answer Choice:CChoice A:Black holes that have orbiting rings of gas with radii greater than 49 kilometers are usually stationary. Choice B:Only rings of gas that are in stable orbits around black holes emit flickering X-rays. Choice C:The black hole that is within the ring of gas observed by the astronomers is spinning. Choice D:X-rays emitted by rings of gas orbiting black holes cause those black holes to spin. Choice E:A black hole is stationary only if it is orbited by a ring of gas with a radius of more than 49 kilometers.