The correct answer is: A. a-1, b-2, c-3, d-4
Kalyanpur Cements Ltd is a cement factory located in Banjari, Bihar. Harabhara Fertilizer is a fertilizer factory located in Dhanukagra, Bihar. Bharat Wagon and Engg. Co. Ltd is a foundry located in Muzaffarpur, Bihar. Indian Oil Corporation is a petroleum refinery located in Barauni, Bihar.
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 construction. Fertilizer is a substance that is added to soil to improve its fertility and increase crop yields. Foundry is a factory where metal is cast into shapes. Petroleum refinery is a factory where crude oil is processed into gasoline, diesel fuel, and other products.