The correct answer is (a) Trombay.
Heavy water is a form of water that contains a higher proportion of the heavier isotope of hydrogen, deuterium, than ordinary water. It is used in nuclear reactors as a moderator to slow down neutrons, and in research as a solvent.
The Bhabha Atomic Research Centre (BARC) in Trombay, Mumbai, is the largest nuclear research centre in India. It was established in 1954 by Homi Jehangir Bhabha, the father of the Indian nuclear program. BARC is responsible for the design, development, and construction of nuclear reactors in India. It also conducts research in nuclear physics, nuclear chemistry, and nuclear engineering.
The Heavy Water Plant at BARC is the only heavy water plant in India. It was commissioned in 1962 and has a capacity of producing 200 tonnes of heavy water per year. The plant uses the electrolysis of water to produce heavy water.
The other options are incorrect. Assam is a state in north-eastern India. Delhi is the capital of India. Bhilai is a city in the Indian state of Chhattisgarh.