Question: who does the beef it's what's for dinner commercials
[{'answer': 'National Livestock and Meat Board', 'provenance': [{'wikipedia_id': '17083868', 'title': "Beef. It's What's for Dinner", 'start_paragraph_id': 3, 'start_character': 72, 'end_paragraph_id': 3, 'end_character': 105, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'answer': 'Leo Burnett Company', 'provenance': [{'wikipedia_id': '17083868', 'title': "Beef. It's What's for Dinner", 'start_paragraph_id': 3, 'start_character': 189, 'end_paragraph_id': 3, 'end_character': 208, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'answer': 'Robert Mitchum', 'provenance': [{'wikipedia_id': '17083868', 'title': "Beef. It's What's for Dinner", 'start_paragraph_id': 3, 'start_character': 334, 'end_paragraph_id': 3, 'end_character': 348, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '17083868', 'title': "Beef. It's What's for Dinner", 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 537, 'bleu_score': 0.9776501033621461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11940297533894901330}, 'section': 'Section::::History.\n'}]}]