Question: who is the guest judge on americas got talent
[{'answer': 'Ken Jeong', 'provenance': [{'wikipedia_id': '4829129', 'title': "America's Got Talent", 'start_paragraph_id': 67, 'start_character': 609, 'end_paragraph_id': 67, 'end_character': 618, 'bleu_score': 1.0, 'section': 'Section::::Season synopses.:Season 13 (2018).\n'}]}, {'answer': 'Olivia Munn', 'provenance': [{'wikipedia_id': '4829129', 'title': "America's Got Talent", 'start_paragraph_id': 67, 'start_character': 620, 'end_paragraph_id': 67, 'end_character': 631, 'bleu_score': 1.0, 'section': 'Section::::Season synopses.:Season 13 (2018).\n'}]}, {'answer': 'Martina McBride', 'provenance': [{'wikipedia_id': '4829129', 'title': "America's Got Talent", 'start_paragraph_id': 67, 'start_character': 633, 'end_paragraph_id': 67, 'end_character': 648, 'bleu_score': 1.0, 'section': 'Section::::Season synopses.:Season 13 (2018).\n'}]}, {'answer': 'Chris Hardwick', 'provenance': [{'wikipedia_id': '4829129', 'title': "America's Got Talent", 'start_paragraph_id': 65, 'start_character': 85, 'end_paragraph_id': 65, 'end_character': 99, 'bleu_score': 1.0, 'section': 'Section::::Season synopses.:Season 12 (2017).\n'}]}]