Question: what is the deepest canyon in north america
[{'answer': 'Hells Canyon', 'provenance': [{'wikipedia_id': '165704', 'title': 'Hells Canyon', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '165704', 'title': 'Hells Canyon', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 229, 'bleu_score': 0.7462973112950531, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1996936427248235636}, 'section': 'Section::::Abstract.'}]}]