Which of the following is an example of an epigenetic change?
A. A nucleotide mutation in a coding region that leads to an amino acid change in gene x.
B. A change in a distal element that leads to a lower transcription level for gene x.
C. A nucleotide change that leads to the mis-splicing of gene x's mRNA.
D. A change in the methyl group of a histone tail associated with gene x.
E. A change in a microRNA binding site that affects the translation of gene x.