The correct answer is: Kutch.
Lignite is a type of coal that is less mature than bituminous coal and anthracite. It is found in sedimentary rocks and is formed from the remains of plants that have been buried and subjected to heat and pressure over millions of years. Lignite is a relatively soft coal that has a high moisture content. It is used primarily for generating electricity and for producing coke.
Gujarat has significant lignite reserves, which are primarily located in the Kutch region. The Kutch lignite basin is one of the largest lignite basins in India. It is estimated to contain about 10 billion tonnes of lignite reserves. The lignite in the Kutch basin is of good quality and is suitable for use in power generation.
The other options are incorrect because they are not the regions in Gujarat where lignite reserves are primarily located. South Gujarat is a region in Gujarat that is known for its oil and gas reserves. Saurashtra is a region in Gujarat that is known for its iron ore reserves. North Gujarat is a region in Gujarat that is known for its agricultural products.