Answer : 3. "Gujarat"
Explanation :

The fourth unit of Kakrapar Atomic Power Project (KAPP-4) in Gujarat with a capacity of 700 MW has recently achieved criticality, marking the beginning of a controlled fission chain reaction. The Kakrapar facility houses the largest indigenous nuclear power reactor built by Nuclear Power Corporation of India Limited (NPCIL). These pressurized heavy water reactors (PHWRs) use natural uranium as fuel and heavy water as coolant and moderator. NPCIL is a Public Sector Undertaking of the Department of Atomic Energy which already operates indigenous PHWRs at other facilities.