Question: what is the top layer of earth's atmosphere
[{'answer': 'Exosphere', 'provenance': [{'wikipedia_id': '202898', 'title': 'Atmosphere of Earth', 'start_paragraph_id': 16, 'start_character': 11, 'end_paragraph_id': 16, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Stratification.\n'}]}]