I am not sure about the complete question what you mean but i think it is 1) can not be used to correct most run-on sentences.
Answer:
The answer would be “those two devised this plan”.
Explanation:
Sensitivity to the sound structure of words
It’s the ability to recognize and work with sounds in a spoken language.
Your answer would be phrase. Hope I helped!
C seems to have the best answer, as alliteration has the same sound at the beginning/or starts with the same letter. Example in the sentence; "sly serpent" and "Standing steadfast". Hope this helps!