Answer:
C. The region that codes for RNA unfolds.
Step-by-step explanation:
Chromosome represents packing of DNA with help of histone and other proteins. Tight packing of DNA and condensation into chromosomes make the RNA coding region of DNA inaccessible for RNA polymerase resulting in decreased rate of transcription. On the other hand, loose packing of DNA with histone proteins and unfolding of chromosomes expose the RNA coding region for enzymes and factors of transcription leading to increased rate of transcription.