(A) One perplexing result of General Relativity is the prediction that gravitational singularities lie at the hearts of black holes, a point where the laws of physics no longer seem to apply, and that has been supported by subsequent research.
"gravitational singularities lie at the hearts of black holes, a point where" "a point" can't refer back to plural subject hearts of blackholes .incorrect
(B) One perplexing result of General Relativity is the prediction at the heart of each black hole of a gravitational singularity, a point at which the laws of physics no longer seem to apply, but a prediction that has been supported by subsequent research.
"prediction at the heart of each black hole of a gravitational singularity"
doesn't make any sense.
furthermore " a point at which". which point? incorrect
(C) One of the perplexing results of General Relativity is the prediction, supported by subsequent research, that at the heart of each black hole lies a gravitational singularity, a point at which the laws of physics no longer seem to apply.
seems clear . hold on to it
(D) The prediction of a gravitational singularity at the heart of each black hole, a perplexing result of General Relativity but one that is supported by subsequent research, is a point where the laws of physics no longer seem to apply.
one what???"is a point where" is too far to modify the heart of the blackhole. incorrect
(E) The prediction that at the heart of each black hole lies a gravitational singularity, a point at which the laws of physics no longer seem to apply, is a perplexing result of General Relativity but supported by subsequent research
the prediction..."is a perplexing..but supported by .." not parallel
IMO C