This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cellular Pathology, Subject name: Pathology
The most-commen form of DNA variation is? 
Select and explain. 
A. Single nucleotide polymorphism, B. Copy Number Variations (CNVs), C. Transposons, D. Mutations
A: Single nucleotide polymorphism
Answer: A: Single nucleotide polymorphism 
Explanation: Ans. (a) Single nucleotide polymorphism(Ref: R 9th/pg 3)Single-Nucleotide Polymorphisms (SNPs)*Variations at single nucleotide positions Q*Most prevalent Q and important form of genetic variation.*Always bi-allelic Q*Can occur in exons, introns, intergenic regions and coding regions*1 % of SNPs occur in coding regions