Question: where the biggest salt mine located in pakistan
[{'answer': 'Khewra', 'provenance': [{'wikipedia_id': '3023054', 'title': 'Khewra Salt Mine', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 6, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'north of Pind Dadan Khan', 'provenance': [{'wikipedia_id': '3023054', 'title': 'Khewra Salt Mine', 'start_paragraph_id': 1, 'start_character': 63, 'end_paragraph_id': 1, 'end_character': 87, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3023054', 'title': 'Khewra Salt Mine', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 670, 'bleu_score': 0.670008251659817, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10429558553449675490}, 'section': 'Section::::Abstract.'}]}]