الشَّاهِدُ — الْقَرِينَةُ — حَدُّ الْحُكْمِ
Passage, indicator, and limit of judgment.
If an exercise supplies only part of a line, its full rhyme, transition, or opening–ending correspondence may not be visible. A disciplined answer states the limit: “This device is established from the excerpt; the other requires the full structure.”
The strongest analysis is limited by the evidence actually supplied. Inserting a word into a proposed revision does not establish a new reading of the original text.