Which one of the following biosphere reserves is spread over three States in India?

The Nilgiri Biosphere Reserve is the only one among the options that is spread across three Indian states: Tamil Nadu, Kerala, and Karnataka [3]. Established in 1986 as India's first biosphere reserve, it encompasses approximately 5,520 sq. km, with 2,537.6 sq. km in Tamil Nadu, 1,527.4 sq. km in Karnataka, and 1,455.4 sq. km in Kerala [3]. In contrast, the Achanakmar-Amarkantak Biosphere Reserve is spread over two states, Madhya Pradesh and Chhattisgarh [5]. The Agasthyamalai Biosphere Reserve is also shared by two states, Kerala and Tamil Nadu [3]. The Seshachalam Hills Biosphere Reserve is located entirely within the state of Andhra Pradesh [2]. Therefore, Nilgiri is the correct answer as it is the only reserve listed that spans three distinct state jurisdictions.

Sources

1. [2] https://satheessc.iitk.ac.in/sathee-ssc/student-corner/general-knowledge/static-awareness/list-of-biosphere-reserve-in-india/
2. [3] http://kerenvis.nic.in/Database/BiosphereReservesinKerala_1293.aspx?format=Print
3. [4] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > 5. Biosphere > p. 433
4. [5] https://tfri.icfre.gov.in/AABR/Presentations/In%20House%20Seminar-%20AABR%2012.12.14.pdf
5. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 4: BIODIVERSITY > zoning of Biosphere reserves > p. 37