Question: what was the oxygen revolution which took place
[{'answer': 'Great Oxygenation Event', 'provenance': [{'wikipedia_id': '3268926', 'title': 'Great Oxidation Event', 'start_paragraph_id': 1, 'start_character': 59, 'end_paragraph_id': 1, 'end_character': 82, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]