Question: who is the oldest senator currently serving in congress
[{'answer': 'Dianne Feinstein', 'provenance': [{'wikipedia_id': '9616751', 'title': 'List of longest-living United States Senators', 'start_paragraph_id': 1, 'start_character': 377, 'end_paragraph_id': 1, 'end_character': 393, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '9616751', 'title': 'List of longest-living United States Senators', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 478, 'bleu_score': 0.9304844600065421, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12670717224604918491}, 'section': 'Section::::Abstract.'}]}]