18. 下列何者為串聯式燃油淨油系統的正確順序? (A) Settling tank → Pre-heater → Clarifier → Purifier → Daily tank (B) Settling tank → Pre-heater → Purifier→ Clarifier (C) Pre-heater→ Settling tank → Clarifier → Daily tank →Purifier→ Daily tank (D) Pre-heater → Settling tank →Purifier → Clarifier → Daily tank