When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity? a. DNA supercoiling at or around H_1 b. methylation and phosphorylation of histone tails c. hydrolysis of DNA molecules where they are wrapped the nucleosome core d. All of the above

This is through the process of methylation and phosphorylation of histones tails.

Explanation:

The addition of   a methyl group  to the amino acid of the histones of the  nucleosomes   that compacted DNA  in the nucleus is  called mehtylation, while the addtion of phodpahte is phosphorylation

Its  effects  on  gene expression depends on the number of methyl groups, and type of amino acid that  methylated. During transcription.

The DNA double strands are compacted and therefore  hidden  from transcription factors and enzymes of transcription by the hitones  tails of the neuclosomes, Methylation  weaken the binding bonds between the tails and DNA structure ; thereby aiding the uncoiling of DNA  from the  tails.(nucleosomes).This chemical  reaction  aided  DNA  strands  exposure   to transcription factors and enzymes, for initiation of transcription. This explains the dyanmic activity of methylation

Futhermore phophorylation also favours unwrapping of DNA, by imitating   modifying enzymes e.g H3Y41E and H3T45E  and convert it to→→ H3Y41phopspahte to aid DNA unwrapping and accessibility to  transcription factors and RNA polymerase Enzymes,