Butyrate can function as ： A: protein methylation B: Protein acetylation C: Protein phosphorylation D: Protein deacetylation

以下哪个与基因表达激活有关 (Which of the following is associated with activation of gene expression ?) A: H3K4甲基化 (H3K4 methylation) B: H3K9甲基化 (H3K9 methylation) C: DNA promoter的甲基化 (Methylation of DNA promoter) D: 组蛋白的去乙酰化 (Deacetylation of histones)