This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Which of the following is not an example of epigenetic change? 
Select and explain. 
A. Histone acetylation, B. Poly A tailing, C. Si RNA interference, D. Splicing DNA methylation
C: Si RNA interference
Answer: C: Si RNA interference 
Explanation: Epigenetic Modifications - This is a mechanism that results in stable propagation of gene activity states from one generation of cells to the next. The epigenetic modifications include changes in histones and DNA methylation. Epigenetic states can be modified by environmental factors which may result in the expression of abnormal phenotypes. These epigenetic modifications control gene expression and changes are also inherited. The epigenome is represented by methyl groups attached to DNA base cytosine and ceain covalent modifications in histones. Ref: DM VASUDEVAN'S TEXTBOOK OF BIOCHEMISTRY,SIXTH EDITION, PG.NO.,511.