Dadri, Chunar, Churk and Dalla, all have factories producing:

Cement
Sugar.
Paper
Fertilizer

The correct answer is (a) Cement.

Dadri, Chunar, Churk and Dalla are all located in the state of Uttar Pradesh, India. Dadri is home to a cement plant operated by UltraTech Cement Limited. Chunar is home to a cement plant operated by ACC Limited. Churk is home to a cement plant operated by Dalmia Bharat Limited. Dalla is home to a cement plant operated by LafargeHolcim India Limited.

Cement is a building material made from limestone, clay, sand, and gypsum. It is used to make concrete, which is a strong and durable material that is used in the construction of buildings, roads, and bridges.

Sugar is a sweet, crystalline substance that is made from sugarcane or sugar beets. It is used in a variety of food products, including candy, baked goods, and beverages.

Paper is a thin, flexible material that is made from wood pulp. It is used for a variety of purposes, including writing, printing, and packaging.

Fertilizer is a substance that is added to soil to improve its ability to grow crops. It can be made from a variety of materials, including natural resources such as guano and bone meal, and synthetic chemicals such as ammonium nitrate and urea.