49. When DNA is compacted by histones into 10 nm and 30 nm fibers, the DNA is unable to interact withproteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin mustconstantly alter its structure. Which processes contribute to this dynamic activity?
(A) DNA supercoiling at or around Hl
(B) methylation and phosphorylation of histone tails
(C) hydrolysis of DNA molecules where they are wrapped around the nucleosome core
(D) accessibility of heterochromatin to phosphorylating enzymes
(E) nucleotide excision and reconstruction