Question: when did the undertaker return as the american badass
[{'answer': 'May 2000', 'provenance': [{'wikipedia_id': '345792', 'title': 'The Undertaker', 'start_paragraph_id': 36, 'start_character': 17, 'end_paragraph_id': 36, 'end_character': 25, 'bleu_score': 1.0, 'section': 'Section::::Professional wrestling career.:World Wrestling Federation/Entertainment/WWE.:American Bad Ass (2000–2001).\n'}]}, {'provenance': [{'wikipedia_id': '345792', 'title': 'The Undertaker', 'start_paragraph_id': 36, 'start_character': 0, 'end_paragraph_id': 36, 'end_character': 698, 'bleu_score': 0.9829771687435411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9035020012452970656}, 'section': 'Section::::Professional wrestling career.:World Wrestling Federation/Entertainment/WWE.:American Bad Ass (2000–2001).\n'}]}]