In astronomy the term "red shift" denotes the extent to which light from a distant galaxy has been shifted toward the red, or long-wave, end of the light spectrum by the rapid motion of the galaxy away from the Earth.

Which of the following represents the most grammatically correct way to express the underlined portion of the sentence above?

to which light from a distant galaxy has been shifted

to which light from a distant galaxy has shifted

that light from a distant galaxy has been shifted

of light from a distant galaxy shifting

of the shift of light from a distant galaxy