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
Most common skin manifestation of radiotherapy: 
Select and explain. 
A. Erythema, B. Atopy, C. Hyperpigmentation, D. Dermatitis
A: Erythema
Answer: A: Erythema 
Explanation: Ans. Erythema