which one of the statements most accurately describes dna methylation? methyl groups are most often added to cytosines adjacent to guanine bases in or near the promoter sequence, decreasing the probability of gene expression. methyl groups are most often added to cytosines adjacent to guanine bases in or near the promoter sequence, increasing the probability of gene expression. methyl groups are most often added to adenine-thymine base pairs, and this increases the probability of gene expression. methyl groups are added to most bases in the promoter region of a specific gene so that rna polymerase and its associated proteins will bind more efficiently. methyl groups are most often added to guanines adjacent to cytosines bases in or near the promoter sequence, increasing the probability of gene expression.