The correct answer is: a) Salt Range Hills.
Sandstone is a sedimentary rock composed of sand-sized grains of mineral, rock, or organic material. It is the most common type of sandstone in the world. Sandstone is quarried in many parts of the world, but the Salt Range Hills in Pakistan are one of the most important sources of sandstone. The Salt Range Hills are a mountain range located in the Punjab province of Pakistan. The range is about 200 kilometers long and 50 kilometers wide. The Salt Range Hills are composed of sandstone, limestone, and shale. The sandstone in the Salt Range Hills is a high-quality building stone. It is used for a variety of purposes, including construction, landscaping, and monuments.
The other options are incorrect because they are not sources of sandstone. The Kandi region of Punjab is a semi-arid region located in the Punjab province of Pakistan. The region is characterized by its sandy soils and low rainfall. The central plains with alluvial soils are located in the central part of Pakistan. The plains are composed of alluvial soil, which is a type of soil that is deposited by rivers. Wetland areas are areas of land that are saturated with water. Wetland areas are not sources of sandstone.