b.they are repetitious lines
Both the lines "Rage, rage against the dying of the light" and "Rode the six hundred" both repeat in their poems. However, neither of them repeat at the end of every stanza. "Rage, rage against the dying of the light" trades with "Do not go gentle into that good night" for the last line of each stanza. "Rode the six hundred" is the last line of the first three stanzas. "Rage, rage against the dying of the light" does not end a sestet. The lines also do not begin an octave.
