Question: who was the sultan of delhi when they invented the city
[{'answer': 'Qutb al - Din Aibak', 'provenance': [{'wikipedia_id': '295402', 'title': 'Delhi Sultanate', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::Dynasties.:Mamluk (Slave).\n'}]}]