Question: when did british columbia became a province of canada
[{'answer': 'July 20 , 1871', 'provenance': [{'wikipedia_id': '3392', 'title': 'British Columbia', 'start_paragraph_id': 85, 'start_character': 206, 'end_paragraph_id': 85, 'end_character': 220, 'bleu_score': 1.0, 'section': 'Section::::History.:Rapid growth and development.\n'}]}, {'provenance': [{'wikipedia_id': '3392', 'title': 'British Columbia', 'start_paragraph_id': 85, 'start_character': 0, 'end_paragraph_id': 85, 'end_character': 510, 'bleu_score': 0.976327165973018, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16789491833126213201}, 'section': 'Section::::History.:Rapid growth and development.\n'}]}]