The correct answer is: A. Zarkul Canal.
King Zain-ul-Abidin was a 14th-century ruler of the Sultanate of Kashmir. He is known for his many public works projects, including the construction of the Zarkul Canal. The canal was built to irrigate the fields of the Kashmir Valley and is still in use today.
The Mahind Canal was built by King Lalitaditya Muktapida in the 8th century. It is one of the oldest canals in the world and is still in use today. The Nandikul Canal was built by King Harshavardhana in the 7th century. It is located in the Indian state of Uttar Pradesh and is no longer in use.
The Zarkul Canal is a major irrigation canal in the Kashmir Valley. It was built by King Zain-ul-Abidin in the 14th century. The canal is about 100 kilometers long and irrigates over 100,000 hectares of land. The canal is fed by the Jhelum River and is one of the most important sources of irrigation in the Kashmir Valley.