Question: which group of plants can be used as indicators of so2 pollution of air
[{'answer': 'Fungi', 'provenance': [{'wikipedia_id': '1859694', 'title': 'Bioindicator', 'start_paragraph_id': 17, 'start_character': 297, 'end_paragraph_id': 17, 'end_character': 302, 'bleu_score': 1.0, 'section': 'Section::::Plant indicators.\n'}]}, {'answer': 'Bacteria'}]