Question: what river carved the mile deep channel that is the grand canyon
[{'answer': 'Colorado River', 'provenance': [{'wikipedia_id': '46989', 'title': 'Grand Canyon', 'start_paragraph_id': 1, 'start_character': 135, 'end_paragraph_id': 1, 'end_character': 149, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '46989', 'title': 'Grand Canyon', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 248, 'bleu_score': 0.548696070440553, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6308809770197377657}, 'section': 'Section::::Abstract.'}]}]