Question: what was the biggest mass extinction in geologic time
[{'answer': 'Permian -- Triassic extinction event'}, {'provenance': [{'wikipedia_id': '9813', 'title': 'Extinction event', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 938, 'bleu_score': 0.9867102250666441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10516484963447501388}, 'section': 'Section::::Major extinction events.\n'}]}]