Question: where does blood flow have the highest velocity
[{'answer': 'Aorta', 'provenance': [{'wikipedia_id': '275216', 'title': 'Hemodynamics', 'start_paragraph_id': 45, 'start_character': 53, 'end_paragraph_id': 45, 'end_character': 58, 'bleu_score': 1.0, 'section': 'Section::::Blood flow.:Cardiac output.\n'}]}]