Question: what were the names of the group abba
[{'answer': 'Benny Andersson', 'provenance': [{'wikipedia_id': '880', 'title': 'ABBA', 'start_paragraph_id': 1, 'start_character': 96, 'end_paragraph_id': 1, 'end_character': 111, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Agnetha Fältskog', 'provenance': [{'wikipedia_id': '880', 'title': 'ABBA', 'start_paragraph_id': 1, 'start_character': 63, 'end_paragraph_id': 1, 'end_character': 79, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Björn Ulvaeus', 'provenance': [{'wikipedia_id': '880', 'title': 'ABBA', 'start_paragraph_id': 1, 'start_character': 81, 'end_paragraph_id': 1, 'end_character': 94, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Anni - Frid Lyngstad ( Frida )'}]