Hey there

If you have done your 12th in pcm the ofcourse you are eligible but only if your age permits as per the NDA eligibility age.

Check details of eligibility of NDA

https://www.google.com/url?sa=t&source=web&rct=j&url=https://competition.careers360.com/articles/nda-eligibility-criteria/amp&ved=2ahUKEwj1yvWWm6LkAhUP4o8KHRiWD-MQFjAcegQIBBAB&usg=AOvVaw1I0C9hFQPh7j-5oJDaK70E&ampcf=1

Good luck