Question: when did alexander graham bell invented the photophone
[{'answer': 'February 19 , 1880', 'provenance': [{'wikipedia_id': '51160', 'title': 'Photophone', 'start_paragraph_id': 16, 'start_character': 3, 'end_paragraph_id': 16, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::First successful wireless voice communications.\n'}]}, {'provenance': [{'wikipedia_id': '51160', 'title': 'Photophone', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 378, 'bleu_score': 0.9679895851501501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17652538638841736607}, 'section': 'Section::::Abstract.'}]}]