Question: when did california become part of the us
[{'answer': 'on September 9 , 1850', 'provenance': [{'wikipedia_id': '5407', 'title': 'California', 'start_paragraph_id': 5, 'start_character': 515, 'end_paragraph_id': 5, 'end_character': 536, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'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': 294854554924541753}, 'section': 'Section::::Abstract.'}]}]