Question: what is the largest mountain free land area in europe
[{'answer': 'The European Plain', 'provenance': [{'wikipedia_id': '11293907', 'title': 'European Plain', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '11293907', 'title': 'European Plain', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 284, 'bleu_score': 0.959574895300321, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17633361610021247327}, 'section': 'Section::::Abstract.'}]}]