Chiasmata are formed during meiosis

The correct option is A Before metaphase I

• Meiosis is divided into 2 parts meiosis 1 and meiosis 2.
• The meiosis 1 is where the recombination between the non sister chromatids takes place and the genetic material is halved compared to the mother cell.
• In zygotene stage of prophase 1 of meiosis 1 is the stage where the crossing over of the chromosomes takes place.
• The chiasmata is the site where the chromatid of the non sister chromatids stay connected even after. The chromosomes have moved away.
• After the crossing over is finished the chromosomes are connected remain connected at the site of chiasmata.
• This takes places in prophase which is the phase before the metaphase 1.
• Therefore the answer option 'Before metaphase I' is correct.