Question: which is the richest football in the world
[{'answer': 'Manchester United', 'provenance': [{'wikipedia_id': '12164751', 'title': "Forbes' list of the most valuable football clubs", 'start_paragraph_id': 27, 'start_character': 12, 'end_paragraph_id': 27, 'end_character': 29, 'bleu_score': 1.0, 'section': 'Section::::Historic rankings.:2008 rankings.\n'}]}]