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
On 4 Gy dose on the scalp, alopecia develops within: 
Select and explain. 
A. 3-4 wk, B. 6-8 wk, C. 10-12 wk, D. 14-16 wk
A: 3-4 wk
Answer: A: 3-4 wk 
Explanation: None