✅ In option A, "that" functions as an indemonstrative pronoun because it refers back to the entire preceding clause: "She argued tirelessly for the new policy." It stands alone as a noun substitute, pointing to a specific, previously mentioned idea or action.

❌ In option B, "that" acts as a subordinating conjunction, introducing a noun clause ("that the innovative design would maximize natural light") which serves as the direct object of the verb "explained."

❌ In option C, "that" is a demonstrative adjective because it modifies the noun phrase "particular shade of blue," indicating which specific shade is preferred rather than standing in for a noun.

❌ In option D, "that" is again a subordinating conjunction, introducing a noun clause ("that honesty was always the best approach") functioning as the direct object of the verb "believed."