Question: what is the active ingredient in green tea
[{'answer': 'Tea leaves', 'provenance': [{'wikipedia_id': '262676', 'title': 'Green tea', 'start_paragraph_id': 5, 'start_character': 341, 'end_paragraph_id': 5, 'end_character': 351, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]