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: Surgery
Which of the following Trinucleotide repeat mutation is present in Huntington's disease? 
Select and explain. 
A. CGG, B. GAA, C. CTG, D. CAG
D: CAG
Answer: D: CAG 
Explanation: CAG Disease Repeat Fragile-X syndrome Freidrich ataxia Myotonic dystrophy Huntington disease CGG GAA CTG CAG