This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
All of the following are used as sclerosing agents for haemorrhoids, EXCEPT: 
Select and explain. 
A. Phenol in olive oil, B. Sodium morrhuate, C. Quinine urea, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: The injection of bleeding internal hemorrhoids with sclerosing agents is another effective office technique for treatment of first-, second-, and some third-degree hemorrhoids. One to 3 mL of a sclerosing solution (phenol in olive oil, sodium morrhuate, or quinine urea) is injected into the submucosa of each hemorrhoid. Few complications are associated with sclerotherapy, but infection and fibrosis have been repoed. Ref: Schwaz's principle of surgery 9th edition, chapter 39.