Question: when did california become part of the united states
[{'answer': 'September 9 , 1850', 'provenance': [{'wikipedia_id': '5407', 'title': 'California', 'start_paragraph_id': 34, 'start_character': 142, 'end_paragraph_id': 34, 'end_character': 160, 'bleu_score': 1.0, 'section': 'Section::::History.:Early American statehood period.\n'}]}, {'provenance': [{'wikipedia_id': '5407', 'title': 'California', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 714, 'bleu_score': 0.9282931925186441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2506779978266611581}, 'section': 'Section::::Abstract.'}]}]