Question: where is pepsin most active in the body
[{'answer': 'stomach', 'provenance': [{'wikipedia_id': '169118', 'title': 'Pepsin', 'start_paragraph_id': 1, 'start_character': 120, 'end_paragraph_id': 1, 'end_character': 127, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '169118', 'title': 'Pepsin', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 1289, 'bleu_score': 0.9066373731746661, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17909854683630667518}, 'section': 'Section::::Activity and stability.\n'}]}]