Since, the chromosomes have been coiled up and condensed, we know that the DNA, present as loosely held together DNA have been replicated and as a result in prophase the chromosomes form as a result of the folding and condensing of the chromatin to produce these thick structures, since they are not aligned near the centre of the cell, we know that the stage the onion cell is in is prophase.
The solution is prophase of mitosis.
