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: Radiology
The radiation tolerance of whole liver is: 
Select and explain. 
A. 15 Gy, B. 30 Gy, C. 40 Gy, D. 45 Gy
C: 40 Gy
Answer: C: 40 Gy 
Explanation: Maximal tolerance dose (TD50/5) of liver is 40 Gy. Ref: X. Allen Li (2011), Chapter 20, "Adaptive Radiation Therapy for Liver Cancer", In the Book, "Adaptive Radiation Therapy", USA, Page 317 ; Clinical Radiation Oncology By Gunderson and Tepper, Page 715