Question: on the banks of which are the capital cities of austria serbia and hungary located
[{'answer': 'The Danube', 'provenance': [{'wikipedia_id': '21209639', 'title': 'Danube', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 10, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]