Question: who is the highest ranking member of the senate
[{'answer': 'president pro tempore', 'provenance': [{'wikipedia_id': '6641520', 'title': 'Seniority in the United States Senate', 'start_paragraph_id': 5, 'start_character': 16, 'end_paragraph_id': 5, 'end_character': 37, 'bleu_score': 1.0, 'section': 'Section::::Benefits of seniority.\n'}]}, {'provenance': [{'wikipedia_id': '6641520', 'title': 'Seniority in the United States Senate', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 113, 'bleu_score': 0.8852140475440831, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2965896235007660333}, 'section': 'Section::::Benefits of seniority.\n'}]}]