Q. Responding to the public's fascination with-and sometimes undue alarm over-possible threats from asteroids, a scale developed by astronomers rates the likelihood that a particular asteroid or comet may collide with Earth.

A. a scale developed by astronomers rates the likelihood that a particular asteroid or comet may
B. a scale that astronomers have developed rates how likely it is for a particular asteroid or comet to
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 or comet will
E. astronomers have developed a scale that rates the likelihood of a particular asteroid or comet that may.

OA C

Please help on this one. I checked the other posts on this SC Q but the post is severely confusing.
I am stuck on C,D,E.

Thanks.