Question: who is the lead singer in casting crowns
[{'answer': 'Mark Hall', 'provenance': [{'wikipedia_id': '1467470', 'title': 'Casting Crowns', 'start_paragraph_id': 1, 'start_character': 99, 'end_paragraph_id': 1, 'end_character': 108, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1467470', 'title': 'Casting Crowns', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 461, 'bleu_score': 0.9751504244977051, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 779528939836244278}, 'section': 'Section::::Abstract.'}]}]