The National Defence Academy (NDA) is a prestigious military training institution in India that trains cadets for the Indian Army, Navy, and Air Force. The academy is located in Khadakwasla near Pune, Maharashtra. It is known for providing a comprehensive training program that includes academic, physical, and military training to groom young men into future military leaders.

The NDA also offers opportunities for foreign cadets to join its training program. These foreign cadets come from friendly nations and undergo the same training as the Indian cadets. They get exposure to the Indian military system, culture, and values, fostering cooperation and understanding among nations.

The correct answer to the question is option 'B' - 1, 3, and 4 only. The NDA does not have foreign cadets from Bangladesh. Let's discuss each country in detail:

1. Bhutan:
Bhutan is a neighboring country of India and has a close and friendly relationship with the Indian government. The NDA has been accepting cadets from Bhutan for several years. The presence of Bhutanese cadets at the NDA helps strengthen the bilateral ties between the two countries and promotes cooperation in defense and security matters.

2. Bangladesh:
Contrary to the options given in the question, the NDA does not have foreign cadets from Bangladesh. Although Bangladesh is a neighboring country of India, it follows a different system for training its military officers.

3. Nepal:
Nepal, another neighboring country of India, has a long-standing tradition of sending cadets to the NDA. The close cultural, historical, and geographical ties between India and Nepal contribute to the presence of Nepalese cadets at the NDA. The exchange of cadets between the two countries helps foster mutual understanding and friendship.

4. Afghanistan:
Afghanistan, despite not being a neighboring country, also sends cadets to the NDA. The presence of Afghan cadets at the NDA reflects the strong bonds between India and Afghanistan. This collaboration aids in sharing military expertise and building a cooperative defense relationship between the two nations.

In conclusion, the NDA has foreign cadets from Bhutan, Nepal, and Afghanistan. It does not have cadets from Bangladesh. The presence of these foreign cadets at the NDA promotes international cooperation, understanding, and friendship among nations.