Question: where do the tigris and euphrates rivers end
[{'answer': 'the Persian Gulf', 'provenance': [{'wikipedia_id': '209798', 'title': 'Tigris–Euphrates river system', 'start_paragraph_id': 1, 'start_character': 182, 'end_paragraph_id': 1, 'end_character': 198, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '209798', 'title': 'Tigris–Euphrates river system', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 351, 'bleu_score': 0.87540210596635, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6503850787143044082}, 'section': 'Section::::Abstract.'}]}]