Concept:Biodiversity hotspots are regions with exceptional concentrations of endemic species and high habitat loss. Silent Valley in Kerala is one such hotspot due to its untouched rainforests.
Explanation:Silent Valley, located in the southern Western Ghats, is among the world's ten "Hottest Biodiversity Hotspots." It is a 8952 sq km forest declared a National Park in 1984 and now part of the Nilgiris Biosphere Reserve. Its isolation by steep ridges and escarpments has preserved it from human interference.
The valley hosts over 960 plant species, 17 on the IUCN Red List, and 315 animal species, including the lion‑tailed macaque. This unmatched richness makes it the most biodiversity‑rich area among the given options.
Other valleys like the Valley of Flowers (in Uttarakhand) are also biodiverse but not as globally significant as Silent Valley.
Answer:C. Silent Valley