The correct answer is option 2, Mongolia. Nomadic Elephant is a joint military exercise conducted between India and Mongolia. This exercise aims to enhance bilateral defense cooperation and interoperability between the two countries. It involves various training activities such as counter-terrorism, hostage rescue, and peacekeeping operations.
Option 1, China, is incorrect as there is no joint military exercise called Nomadic Elephant between India and China. India and China do conduct joint military exercises, but they have different names like Hand-in-Hand and Cooperation Spirit.
Option 3, Vietnam, is also incorrect. India and Vietnam do have defense cooperation, but they do not conduct joint military exercises named Nomadic Elephant.
Option 4, Bhutan, is also incorrect. While India has a strong defense partnership with Bhutan, they do not conduct joint military exercises together called Nomadic Elephant.
In conclusion, the correct answer is option 2, Mongolia, as Nomadic Elephant is a joint military exercise between India and Mongolia.