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
Increasing severity of mental retardation of male members over generations is a result of ? 
Select and explain. 
A. Mitochondrial DNA mutation, B. Frameshift mutation, C. Y linked disorder, D. Trinucleotide repeat mutation
D: Trinucleotide repeat mutation
Answer: D: Trinucleotide repeat mutation 
Explanation: Ans. is 'd' i.e., Trinucleotide repeat mutation