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
In genomic imprinting. DNA is modified by: 
Select and explain. 
A. Acetylation, B. Methylation, C. Phosphorylation, D. Deamination
B: Methylation
Answer: B: Methylation 
Explanation: Ans: B. Methylation(Ref Robbins 9/e p180, 8/e pl)Genomic imprinting:DNA modified by methylation.An epigenetic process resulting in differential inactivation of either maternal or paternal alleles of ceain genes.Mechanism:DNA methylation at CG nucleotide.Histone H4 deacetylation.Methylation.