Question: who did the u 2 spy plane belong to
[{'answer': 'United States', 'provenance': [{'wikipedia_id': '304689', 'title': '1960 U-2 incident', 'start_paragraph_id': 1, 'start_character': 17, 'end_paragraph_id': 1, 'end_character': 30, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '304689', 'title': '1960 U-2 incident', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 393, 'bleu_score': 0.8445923410050261, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2626831980385915978}, 'section': 'Section::::Abstract.'}]}]