The correct answer is C. Hisar.
Hisar is a district in the Indian state of Haryana. It is one of the largest districts in Haryana in terms of area and population. Hisar is also one of the most developed districts in Haryana. The district is known for its agriculture, industry, and education.
Hisar is a major producer of iron pipes. The district has a number of iron pipe manufacturing units. These units produce a variety of iron pipes, including water pipes, gas pipes, and oil pipes. The iron pipes produced in Hisar are of high quality and are exported to a number of countries.
The other options are incorrect. Ambala is a district in the Indian state of Haryana. It is one of the smallest districts in Haryana in terms of area and population. Ambala is not known for its iron pipe production. Panchkula is a district in the Indian state of Haryana. It is a relatively new district and is not known for its iron pipe production. Kurukshetra is a district in the Indian state of Haryana. It is a historical district and is known for its religious significance. Kurukshetra is not known for its iron pipe production.