Question: when did puerto rico become a possession of the united states
[{'answer': '1898', 'provenance': [{'wikipedia_id': '19283151', 'title': 'History of Puerto Rico', 'start_paragraph_id': 3, 'start_character': 3, 'end_paragraph_id': 3, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19283151', 'title': 'History of Puerto Rico', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 614, 'bleu_score': 0.9804854598160591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 440062688584406473}, 'section': 'Section::::Abstract.'}]}]