The graph shows how the rate of transcription (RNA synthesis) changes as a eukaryotic cell progresses through the stages of a single cell cycle.

During which phase of the cell cycle (WWW, XXX, YYY, or ZZZ) does chromosome condensation make DNA highly compacted and physically inaccessible to RNA polymerase, leading to a dramatic reduction in transcription?
Phase XXX
Phase ZZZ
Phase WWW
Phase YYY