Question: solvent extraction method of refining is adopted for which group of baseoil
[{'answer': 'conventional petroleum base oils', 'provenance': [{'wikipedia_id': '43804874', 'title': 'Base oil', 'start_paragraph_id': 8, 'start_character': 111, 'end_paragraph_id': 8, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Official Classifications.:Group I.\n'}]}, {'provenance': [{'wikipedia_id': '43804874', 'title': 'Base oil', 'start_paragraph_id': 8, 'start_character': 26, 'end_paragraph_id': 8, 'end_character': 143, 'bleu_score': 0.791261986372021, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17715872041770726412}, 'section': 'Section::::Official Classifications.:Group I.\n'}]}]