Question: where does the actual gas exchange take place most often
[{'answer': 'lungs', 'provenance': [{'wikipedia_id': '36863', 'title': 'Lung', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 9, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '36863', 'title': 'Lung', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 925, 'bleu_score': 0.9866213202385071, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16986841299448654992}, 'section': 'Section::::Abstract.'}]}]