Pick out the item which has sequential arrangements.
a) Zygotene $\to$ Leptotene $\to$ Pachytene $\to$ Diplotene $\to$ Diakinesis.
b) Diakinesis $\to$ Zygotene $\to$ Leptotene $\to$ Pachytene $\to$ Diplotene
c) Leptotene $\to$ Zygotene $\to$ Pachytene $\to$ Diplotene $\to$ Diakinesis.

Prophase of meiosis I is long and complicated because it is during this phase that crossing over occurs between homologous chromosomes. Prophase I is comprised of Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.

Leptotene --> Zygotene --> Pachytene --> Diplotene --> Diakinesis.

Leptotene- The first stage of the prophase of meiosis, during which each chromosome becomes visible as two chromatids.

Zygotene- Thestageinprophaseofmeiosisduringwhichhomologouschromosomesbecomepaired forming synapsis.

Pachytene- In pachytene, there occurs exchange of the corresponding segments non-sister chromatids of homologous chromosomes. This process is called as crossing over.

Diplotene- A stage of meiotic prophase in which homologous chromosome pairs begin to separate and chiasmata become visible.

Diakinesis- This stage is recognized by the highly condensed condition of the chromosomes, the homologous pair of which are held together by chiasmata. In some organisms, just before or during diakinesis, the chiasmata move to the ends of the chromosome arms.