Question: what was the vector of the bubonic plague
[{'answer': 'fleas', 'provenance': [{'wikipedia_id': '4746', 'title': 'Plague (disease)', 'start_paragraph_id': 23, 'start_character': 120, 'end_paragraph_id': 23, 'end_character': 125, 'bleu_score': 1.0, 'section': 'Section::::Cause.\n'}]}, {'provenance': [{'wikipedia_id': '4746', 'title': 'Plague (disease)', 'start_paragraph_id': 23, 'start_character': 0, 'end_paragraph_id': 23, 'end_character': 935, 'bleu_score': 0.727061239106868, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2269288345364065386}, 'section': 'Section::::Cause.\n'}]}]