Answer:
Metaphase of meiosis I
Explanation:
Crossing-over is a process where a segment of one chromosome is exchanged with its homologous pair. It occurs between the non-sister chromatids of homologous chromosomes after they must have paired up side by side. This process of crossing-over occurs in the Prophase stage of meiosis I.
After crossing-over, which may or may not occur, the spindle fibres (developed from the centrosomes) begins to attach to centromeres of each chromosome and move them towards the center of the cell (metaphase plate). The microtubules attaches to chromosomes in a way that homologous chromosomes and not the individual chromosomes are lined up at the Metaphase plate i.e. center. This process of homologous chromosomes aligning at the Metaphase plate occurs in Metaphase of meiosis I.
It is important to note that the random manner in which the chromosomes (homologous) likes up determines which chromosome gets separated into each cell in the next stage (anaphase).
