How does the association of DNA with histones in the nucleosome inhibit the initiation and elongation stages of transcription?

How does the association of DNA with histones in the nucleosome inhibit the initiation
and elongation stages of transcription?
a. It inhibits the access of enzymes involved in transcription initiation and elongation to
DNA.
b. It activates the access of transcriptional enzymes to DNA.
c. It denatures the DNA in contact with the histones.
d. It degrades the DNA in contact with the histones.

Answer

• a. It inhibits the access of enzymes involved in transcription initiation and elongation to
  DNA.
  Explanation:
  Nucleosomes inhibit transcription initiation by occupying key DNA sequences near the promoter and transcriptional start sites. Nucleosomes are repressors of transcription initiation both in vitro and in vivo. Repressors are proteins that inhibits expression of one or more genes by binding operators on the gene. When nucleosomes fold the gene into a condensed structure, the RNA polymerase cannot access the promoter and can not initiate addition of RNA nucleotides until the structure is unfolded.