Correct Answer:
C. Karachi
The National Oil Refinery of Pakistan is strategically located in Karachi. Karachi is Pakistan's largest city, its primary port, and a major industrial and financial hub. This location provides crucial access to shipping lanes for crude oil imports and efficient distribution of refined products across the country. Locating such a vital industrial facility in Karachi leverages its existing infrastructure and economic significance. Distractors like Lahore, Islamabad, and Multan are important cities but lack the coastal access and extensive industrial infrastructure that makes Karachi the ideal site for a national oil refinery.