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: Pathology
Retinoblastoma gene is located on chromosome ? 
Select and explain. 
A. 6, B. 9, C. 13, D. 21
C: 13
Answer: C: 13 
Explanation: Ans. is 'c' i.e., 13