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
If the radiation exposure occurs before DNA synthesis, the damage manifests: 
Select and explain. 
A. One arm of chromosome, B. Both the arms of chromosome, C. Shorter arm of chromosome, D. None of the arm of chromosome is affected
B: Both the arms of chromosome
Answer: B: Both the arms of chromosome 
Explanation: If radiation exposure occurs after DNA synthesis (i.e., in G2 or mid and late S), only one arm of the affected chromosome is broken.
If radiation induced break occurs before DNA has replicated (i.e., in G1 or early S), the damage manifests in both arms (Chromosome aberration) at the next mitosis.