Question: the central canal of an osteon contains what
[{'answer': "the bone 's blood supplies", 'provenance': [{'wikipedia_id': '1312333', 'title': 'Osteon', 'start_paragraph_id': 3, 'start_character': 162, 'end_paragraph_id': 3, 'end_character': 188, 'bleu_score': 1.0, 'section': 'Section::::Structure.\n'}]}, {'provenance': [{'wikipedia_id': '1312333', 'title': 'Osteon', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 233, 'bleu_score': 0.948006874591591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2356358248992208286}, 'section': 'Section::::Structure.\n'}]}]