The correct option is Tamil Nadu and Kerala
Explanation
The Agasthyamalai Biosphere Reserve (ABR) is a significant protected area located at the southernmost end of the Western Ghats. Established in 2001, it is renowned for its rich biodiversity and high endemism. It was included in the UNESCO World Network of Biosphere Reserves in 2016.
Geographical Distribution:
- The reserve encompasses a total area of approximately 3,500 km² and straddles the border between the states of Kerala and Tamil Nadu.
- In Kerala: It includes the Shendurney Wildlife Sanctuary, Peppara Wildlife Sanctuary, Neyyar Wildlife Sanctuary, and the Achankovil Forest Division.
- In Tamil Nadu: It includes the Kalakkad Mundanthurai Tiger Reserve (KMTR) located in the Tirunelveli and Kanyakumari districts.
Consequently, the reserve is not shared with Karnataka or Andhra Pradesh.
Key Takeaway: The Agasthyamalai Biosphere Reserve is situated in the southern Western Ghats and is shared exclusively between the states of Tamil Nadu and Kerala.