Which one of the following is not an oil refinery (Petroleum) ?

The correct answer is (c), Digboi.

Jamnagar is an oil refinery in Gujarat, India. It is the world’s largest single-location oil refinery, with a capacity of 1.24 million barrels per day.

Jamshedpur is a steel city in Jharkhand, India. It is home to the Tata Steel plant, which is one of the largest steel plants in the world.

Barauni is an oil refinery in Bihar, India. It has a capacity of 600,000 barrels per day.

Digboi is an oil town in Assam, India. It was the first oil refinery in India, and it is still in operation today. However, it is a much smaller refinery than the others mentioned above, with a capacity of only 30,000 barrels per day.