This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Which is not associated with Down's syndrome? 
Select and explain. 
A. Trisomy 21, B. Mosaic 21, C. Robesonian translocation 21/21,14/21, D. Deletion 21
D: Deletion 21
Answer: D: Deletion 21 
Explanation: .