A constructed response is not a guess dressed up in complete sentences. It is a small argument, and like every argument it can be checked. The reader should be able to trace each claim back to a line in the text.
That is why ResponseLab asks students to mark the passage before they write. Highlighting is not decoration; it is the first draft of the evidence. When a student later selects a quotation, the platform compares it against the passage itself, so a sentence that was never written cannot be cited.
Try it here. Select any phrase above or below, choose highlight, underline, or note, and watch it appear in the panel beside the passage.