Question: who was the head of the senate committee that began hearings to investigate the watergate break-in
[{'answer': 'Sam Ervin', 'provenance': [{'wikipedia_id': '52382', 'title': 'Watergate scandal', 'start_paragraph_id': 50, 'start_character': 138, 'end_paragraph_id': 50, 'end_character': 147, 'bleu_score': 1.0, 'section': 'Section::::Cover-up and its unraveling.:Senate Watergate hearings and revelation of the Watergate tapes.\n'}]}, {'provenance': [{'wikipedia_id': '52382', 'title': 'Watergate scandal', 'start_paragraph_id': 50, 'start_character': 0, 'end_paragraph_id': 50, 'end_character': 650, 'bleu_score': 0.8902200714371731, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6723292523532419357}, 'section': 'Section::::Cover-up and its unraveling.:Senate Watergate hearings and revelation of the Watergate tapes.\n'}]}]