The correct answer is D) Citric or sulfamic acid. These acids are the preferred and most commonly used for scale removal from the heating surfaces of the jacket-water heated submerged-tube evaporator. Citric acid and sulfamic acid are preferred because they are less corrosive and safer to handle compared to concentrated sulfuric acid (A) or concentrated hydrochloric acid (B). Muriatic acid (C) is a less desirable option as it is a dilute form of hydrochloric acid. The use of these milder acids helps to prevent damage to the evaporator's components during the descaling process.