Question: when was the last episode of one tree hill aired
[{'answer': 'April 4 , 2012', 'provenance': [{'wikipedia_id': '11158614', 'title': 'List of One Tree Hill episodes', 'start_paragraph_id': 3, 'start_character': 231, 'end_paragraph_id': 3, 'end_character': 245, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]