Answer:
III. Condensation of chromosomes begins.
I. Synapsis occurs.
II. Crossing-over is completed.
IV. Separation of homologous chromosomes begins
Explanation:
The prophase I of meiosis I begins with the condensation of chromosomes. The process of compaction makes the individual chromosomes visible and the stage is called leptotene.
Leptotene is followed by zygotene of prophase I during which the homologous chromosomes are paired together. The process is mediated by the synaptonemal complex. As the homologous chromosomes are paired, each pair is visible as a tetrad as each of the chromosomes of a pair has two sister chromatids.
The exchange of part of chromatids occurs during crossing over. Crossing over is the event of the pachytene stage of prophase I. After crossing over, the homologous chromosomes begin to separate from each other during diplotene but stay paired at the points of crossing over. These points are called chiasmata. Diakinesis of prophase I is marked by the dissolution of chiasmata.
