Question: what element is the most abundant on the earths crust
[{'answer': 'oxygen', 'provenance': [{'wikipedia_id': '392828', 'title': 'Abundance of the chemical elements', 'start_paragraph_id': 2, 'start_character': 30, 'end_paragraph_id': 2, 'end_character': 36, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '392828', 'title': 'Abundance of the chemical elements', 'start_paragraph_id': 28, 'start_character': 0, 'end_paragraph_id': 28, 'end_character': 327, 'bleu_score': 0.9632870032952191, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7706461530729706557}, 'section': 'Section::::Earth.:Crust.\n'}]}]