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: Medicine
Gene for Rh antigen is located on chromosome ? 
Select and explain. 
A. 1, B. 4, C. 9, D. 19
A: 1
Answer: A: 1 
Explanation: Ans. is 'a' i.e., 1