The structure depicted in your question, characterized as "X-shaped," typically represents the duplicated chromosomes (sister chromatids) that are aligned and prepared for separation during mitosis. This X shape is most commonly seen during:
d. end of prophase and metaphase
During the end of prophase, the chromosomes condense and become visible as X-shaped structures (sister chromatids). In metaphase, these X-shaped chromosomes align at the cell's equatorial plane.
In contrast:
- Interphase (option c) is when cells are not in mitosis, so chromosomes are in a less condensed state.
- Early prophase (option b) would not yet have the chromosomes fully formed into their X shape.
- End of anaphase and telophase (option a) is when the sister chromatids have been pulled apart and are no longer in the X-shaped configuration.
Therefore, the correct option is d.