In a particular region in India, the local people train the roots of living trees into robust bridges across the streams. As the time passes, these bridges become stronger. These unique 'living root bridges' are found in

1. A

   Meghalaya

   Living root bridges are grown by the Khasi and Jaintia peoples of Meghalaya, especially in the East Khasi Hills, by training Ficus (rubber-fig) roots across streams. They strengthen with time. This option is the official key.

2. B

   Himachal Pradesh

   Himachal Pradesh has wooden and rope bridges in the Himalaya, not living Ficus root bridges of the Meghalaya type. This option is not the key.

3. C

   Jharkhand

   Jharkhand does not have this living-root-bridge tradition. This option is therefore wrong.

4. D

   Tamil Nadu

   Tamil Nadu has other vernacular bridges and sacred groves, not these living root bridges. This option is not the key.

Summary. Official key is (a) Meghalaya. Double-decker and single living root bridges around Cherrapunji/Sohra and Nongriat are a documented Khasi–Jaintia practice. The humid climate lets aerial roots of Ficus elastica be trained over decades. Himachal, Jharkhand and Tamil Nadu do not host this landscape. Only Meghalaya matches the passage.