Question: when did the us acquire california from mexico
[{'answer': '1848', 'provenance': [{'wikipedia_id': '21073732', 'title': 'Mexican–American War', 'start_paragraph_id': 1, 'start_character': 250, 'end_paragraph_id': 1, 'end_character': 254, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21073732', 'title': 'Mexican–American War', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 545, 'bleu_score': 0.614754663320353, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2960860632304684222}, 'section': 'Section::::Abstract.'}]}]