631190-12-32P AID: 2498 | 25/08/2015
Histone methylation is a process by which methyl groups are added to amino acids of the histone. Histone methylation either increase or decrease gene expression by unwinding or tightly coiling the DNA (deoxyribonucleic acid) around the histone octamer.
DNA methylation is mechanism by which methyl groups are added to the DNA to supress the gene expression. DNA methylation is mainly seen in gene imprinting. Therefore, it is one of the epigenetic marks.
Histone acetylation and deacetylation are processes by which the lysine residues present in the N-terminal tails of histones are acetylated as a part of regulating gene expression.
These three mechanisms are part of epigenetic regulation, and methylation, acetylation function as epigenetic marks.
Hence, the correct option is (d) all of the above are epigenetic marks.