Question: when was the letter to ren an written
[{'answer': '96 BC', 'provenance': [{'wikipedia_id': '27636', 'title': 'Sima Qian', 'start_paragraph_id': 13, 'start_character': 35, 'end_paragraph_id': 13, 'end_character': 40, 'bleu_score': 1.0, 'section': 'Section::::As Han court official.:Later years and death.\n'}]}, {'provenance': [{'wikipedia_id': '27636', 'title': 'Sima Qian', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 267, 'bleu_score': 0.959574895300321, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16505652219456990635}, 'section': 'Section::::As Han court official.:The Li Ling affair.\n'}]}]