Final answer:
The cells in step Y are in metaphase II, where the chromosomes line up in a single line across the spindle. The correct answer is metaphase II.
Step-by-step explanation:
The cells in step Y can best be described as being in metaphase II.
In metaphase II, the chromosomes line up in a single line across the spindle, just like in metaphase of mitosis. Each pair of chromosomes is pulled apart and migrates towards the poles during anaphase II, while sister chromatids separate. Telophase II then reconstitutes the nucleus and followed by cytokinesis.