NDA

Hello bikash. NDA is the most prestigious academy to get into Indian defence services. NDA will get you a reputation that engineering can never get. Moreover, the respect, perks and govt facilities provided to an NDA student are unmatchable. But you need to be clear of the physical exertion you will face in NDA. It is very difficult to live there with studies and physical training both being given equal importance. Many people leave NDA in between and have to pay the bond amount thereby losing all opportunities because they are not able to cope up with the exertion. You need to be extremely determined to go into NDA.
Now engineering does not have reputation and perks even close to NDA, but it is the easier route. You only need to study. Choice is always yours. My opinion- go for NDA if you can.

Hi
As I see your interest in Biotechnology, I would say it's a good choice indeed.
The biotechnology industry is constantly growing; during the past 10 years the number of employees has increased by more than 90 percent! If you enjoy science, math, technology, investigating and solving problems, and making useful products, a career in biotechnology may be for you.
When most people think of opportunities for careers in biotechnology, they think of a scientist in a white coat in a laboratory developing drugs to improve the quality of life. However, biotechnology has a wide variety of career opportunities ranging from sales and marketing, to research and development, to manufacturing and quality control and assurance.
Also, there are many private colleges around who provide Biotech.