Question: what river forms part of the border between two northwestern states and flows into pacific ocean
[{'answer': 'Columbia River', 'provenance': [{'wikipedia_id': '5408', 'title': 'Columbia River', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '5408', 'title': 'Columbia River', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 663, 'bleu_score': 0.937092676608638, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14522350065717388573}, 'section': 'Section::::Abstract.'}]}]