Which of the following is an example of an epigenetic change in eukaryotes? a) a loss of an at base pair from a gene b) the addition of methyl groups to cytosines in the promoter region of a gene c) the substitution of an at base pair by a gc base pair in a gene as a result of a mistake during dna replicationd) a deletion that simultaneously removes two genes from the genome e) none of these examples represents epigenetic changes.