Question: during which phase of meiosis does crossover occur
[{'answer': 'pachytene stage of prophase I', 'provenance': [{'wikipedia_id': '64045', 'title': 'Chromosomal crossover', 'start_paragraph_id': 1, 'start_character': 288, 'end_paragraph_id': 1, 'end_character': 309, 'bleu_score': 0.668740304976422, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '64045', 'title': 'Chromosomal crossover', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 586, 'bleu_score': 0.9205847666823811, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7620154874781181049}, 'section': 'Section::::Abstract.'}]}]