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
Which of the following is least radiosensitive tissue? 
Select and explain. 
A. WBC, bone cells, epithelial cells, B. Muscle cells, nerve cells, bone cells, C. Connective tissue cell, endothelial cell, muscle cell, D. RBC, muscle cell, nerve cell
D: RBC, muscle cell, nerve cell
Answer: D: RBC, muscle cell, nerve cell 
Explanation: None