Question: what ion causes the color of the indicator to change
[{'answer': 'hydronium ions', 'provenance': [{'wikipedia_id': '85411', 'title': 'PH indicator', 'start_paragraph_id': 1, 'start_character': 212, 'end_paragraph_id': 1, 'end_character': 226, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'or hydrogen ions', 'provenance': [{'wikipedia_id': '85411', 'title': 'PH indicator', 'start_paragraph_id': 1, 'start_character': 232, 'end_paragraph_id': 1, 'end_character': 248, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '85411', 'title': 'PH indicator', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1200, 'bleu_score': 0.942360849808846, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9887242375230738506}, 'section': 'Section::::Abstract.'}]}]