Sentence Correction (SC) | Responding to the publics fascination with-and sometimes

For those who are confused between the options C andD, please read the Ron's explanation below ,

Responding to the public’s fascination with-and sometimes undue alarm over-possible threats fromasteroids, a scale developed by astronomers rates the likelihood that a particular asteroid or comet may collide with Earth.
C. astronomers have developed a scale to rate how likely a particular asteroid or comet will be to
D. astronomers have developed a scale for rating the likelihood that a particular asteroid
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