The question asks which option is not an Inter-Services Establishment. An Inter-Services Establishment is an organization or institution that caters to the training and development needs of multiple branches of the defense forces. Let`s examine each option to determine which one does not fit this category.

Option 1: Officers Training Academy (OTA) is the training establishment for officers of the Indian Army. Since it is specific to the Army only, it does not cater to multiple branches and therefore does not qualify as an Inter-Services Establishment.

Option 2: National Defence Academy (NDA) is an Inter-Services Academy where cadets from the Army, Navy, and Air Force undergo joint training. It caters to multiple branches and thus qualifies as an Inter-Services Establishment.

Option 3: National Defence College (NDC) is an Inter-Services Institution that offers strategic education and training to senior officers from the armed forces, civil services, and other allied services. It caters to multiple branches and is considered an Inter-Services Establishment.

Option 4: Armed Forces Medical College (AFMC) is primarily responsible for the education and training of medical officers for the Armed Forces. Since it is specific to medical training and does not encompass multiple branches, it does not qualify as an Inter