India’s oldest iron and steel plant is:

Correct option is A

The correct answer is (A) TISCO at Jamshedpur. 
Explanation:
· The Tata Iron and Steel Company (TISCO) was founded by Jamsetji Tata in 1907 at Sakchi, which is now Jamshedpur.
· The company was established after his son, Dorabji Tata, implemented his vision of a modern steel plant.
· TISCO began production of pig iron in 1911 and started manufacturing steel in 1912, making it the oldest major iron and steel plant in India. 
Information Booster:
· The establishment of TISCO was a significant step in India's industrialization and was a product of the Swadeshi movement.
· The city of Jamshedpur was later renamed after its founder, Jamsetji Tata.
· The plant's location was chosen strategically due to its proximity to coal and iron ore deposits and the availability of water from the Subarnarekha and Kharkai rivers. 
Additional Knowledge: (B) Bokaro Iron and Steel Plant:
· This plant was established much later, in 1964, with the assistance of the Soviet Union.
· It is located in Bokaro, Jharkhand, and is part of the public sector, managed by the Steel Authority of India Limited (SAIL). 
(C) Durgapur Iron and Steel Plant:
· This plant was established in the late 1950s with the help of the United Kingdom.
· It is situated in Durgapur, West Bengal, and is also operated by SAIL. 
(D) Rourkela Iron and Steel Plant:
· This was the first integrated steel plant in the public sector, established in 1959 with collaboration from West Germany.
· It is located in Rourkela, Odisha, and is operated by SAIL.