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
Cells are most sensitive to radiation in: 
Select and explain. 
A. G2 phase, B. G1 phase, C. G1 phase and early S phase, D. G2 phase and late S phase
A: G2 phase
Answer: A: G2 phase 
Explanation: None