Question: which of the gauges is used by railway in the hilly areas
[{'answer': 'Narrow gauge', 'provenance': [{'wikipedia_id': '21932', 'title': 'Narrow-gauge railway', 'start_paragraph_id': 18, 'start_character': 238, 'end_paragraph_id': 18, 'end_character': 250, 'bleu_score': 1.0, 'section': 'Section::::Advantages.\n'}]}, {'provenance': [{'wikipedia_id': '21932', 'title': 'Narrow-gauge railway', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 626, 'bleu_score': 0.735385338860703, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6557853431453599236}, 'section': 'Section::::Advantages.\n'}]}]