Question: where is the origin of the rock river
[{'answer': 'Horicon Marsh', 'provenance': [{'wikipedia_id': '563180', 'title': 'Rock River (Mississippi River tributary)', 'start_paragraph_id': 2, 'start_character': 66, 'end_paragraph_id': 2, 'end_character': 79, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]