The correct answer is option 2: Soviet Union. Bhilai Steel Plant, located in Chhattisgarh, India, was built in collaboration with the Soviet Union. The plant was established in the 1950s as part of India`s plans for industrialization and self-sufficiency in steel production. The Soviet Union provided technical assistance, expertise, and equipment for the construction and operation of the plant. This collaboration helped in the development of a modern steel complex and played a crucial role in meeting the growing demand for steel in India. The Bhilai Steel Plant has since become one of the largest and most successful steel plants in India, contributing significantly to the country`s industrial sector and economic growth.