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
Trinucleotide repeats seen in Huntington disease is? 
Select and explain. 
A. GAA, B. CAG, C. CTG, D. CGG
B: CAG
Answer: B: CAG 
Explanation: GAA - Friedreich ataxia
CAG - huntington disease
CTG - Myotonic dystrophy
CGG - Fragile x syndrome