'Milind Panho' is in the form of a dialogue between King Milind and a Buddhist saint. The concerned saint was:

1. A

   Nagarjun

   Option (a) claims that Nagarjuna was the Buddhist saint in the dialogue. However, Nagarjuna was a later Mahayana philosopher and founder of the Madhyamaka school, not the interlocutor in this text.

2. B

   Nagbhatt

   Option (b) claims that Nagbhatt was the saint in the dialogue. Nagbhatt is actually a historical name associated with early medieval Gurjara-Pratihara rulers, not a Buddhist monk.

3. C

   Nagasena

   Option (c) claims that Nagasena was the Buddhist saint who engaged in philosophical discourse with King Menander, also known as Milinda. This classical Pali text, known as Milinda Panha or the Questions of Milinda, records their profound discussions on Buddhism, making this the correct official key.

4. D

   Kumaril Bhatt

   Option (d) claims that Kumaril Bhatt was the saint in the dialogue. Kumaril Bhatt was a renowned 8th-century philosopher of the Mimamsa school of Hindu philosophy, entirely unrelated to this ancient Buddhist text.

Summary. Official key is (c) Nagasena. The text 'Milind Panho' captures the profound philosophical dialogue between the Indo-Greek King Menander (Milinda) and the wise Buddhist monk Nagasena. Options (a), (b), and (d) incorrectly attribute the text to figures from entirely different historical contexts and philosophical traditions. Therefore, option (c) is the only valid choice.