The Bihar State Hydroelectric Power Corporation was established in 1982 — option 2.

What it does. The corporation, usually abbreviated BSHPC, was set up as a state public-sector undertaking to plan, build and operate hydroelectric generating stations in Bihar. It was registered under the Companies Act with its office at Patna, and it works alongside the Bihar State Power Holding Company, under which generation, transmission and distribution were reorganised in 2012.

The setting. Bihar has no large storage dam sites of its own, since the state lies almost entirely on the flat Gangetic plain and the big Himalayan rivers — the Kosi, Gandak, Bagmati and Kamla — enter it from Nepal already at low gradient. What Bihar does have is a network of barrages and canal falls, so its hydel potential lies chiefly in small and mini hydro plants installed on canal drops. Stations such as those on the Sone canal system at Dehri, and the units at the Kosi barrage at Birpur and the Western Gandak canal at Valmikinagar, are of this type, each of a few megawatts.

Why the corporation matters. Bihar draws most of its electricity from thermal stations and from its share of central-sector plants, so hydro contributes only a small fraction of supply. The corporation’s significance is therefore less in volume than in the fact that canal-based small hydro is renewable, needs no new submergence, and can be built quickly — which is why it has been revived under recent renewable-energy targets.

Hence, the answer is 1982.