The correct option is B pachytene
During zygotene phase of meiosis – I, homologous chromosomes are arranged near to each other this is called synapsis. When synapsis is complete cell enters next phase of meiosis – I, pachytene.
During pachytene the homologous chromosomes thicken and become recombinant. Crossing over of segments of genetic information occurs between non-sister chromatids of homologous chromosomes, forming exchange sites called chiasmata and resulting in recombination.