The Bidon and the Bishop Falls are situated in

State-wise GK questions on the North-East often hinge on matching a named natural landmark (a river, hill, or waterfall) to the state that hosts it — once the landmark is identified, its host state follows directly.

Bishop Falls and Beadon Falls (sometimes rendered "Bidon Falls" in question banks) are twin waterfalls in the Suna Valley near Shillong, East Khasi Hills district. Bishop Falls, fed by the Umshyrphi river, is a three-tiered fall about 135 metres high and ranks among India's tallest waterfalls; Beadon Falls drops nearby into the Umiam river. Both are visible together from the Mawlai viewpoint outside Shillong.

Ruling out the other options by their own well-known landmarks:

• Mizoram's signature waterfall is Vantawng Falls, near Thenzawl — a separate, unrelated landmark.

• Assam is dominated by the Brahmaputra plains; its notable waterfalls, such as Kakochang Falls in Karbi Anglong, are different sites.

• Nagaland's signature natural landmark is the Dzükou Valley in the Naga Hills, a different location entirely.

Since Bishop Falls and Beadon Falls both lie in the East Khasi Hills district, the state is confirmed.