Question: where are the hearts that are used in transplants sourced from
[{'answer': 'a recently deceased organ donor', 'provenance': [{'wikipedia_id': '30876400', 'title': 'Heart transplantation', 'start_paragraph_id': 1, 'start_character': 351, 'end_paragraph_id': 1, 'end_character': 382, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '30876400', 'title': 'Heart transplantation', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 697, 'bleu_score': 0.648524208143984, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3061942040677022822}, 'section': 'Section::::Abstract.'}]}]