题目选项分析

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

Responding to the public's fascination with-and sometimes undue alarm over-possible threats from asteroids, a scale that astronomers have developed rates how likely it is for a particular asteroid or comet to collide with Earth.