The correct answer is option 3, "Nuclear deterrence," as it was not one of the Panch Sheel principles. Panch Sheel, also known as the Five Principles of Peaceful Coexistence, were a set of principles that guided India`s foreign policy in the 1950s. These principles were originally proposed by India and China as a framework for peaceful relations between the two countries.

Option 1, "Peaceful Co-existence," is one of the Panch Sheel principles. It emphasizes the importance of maintaining peaceful relations and resolving conflicts through peaceful means.

Option 2, "Mutual respect for territorial integrity," is also one of the Panch Sheel principles. It stresses the importance of respecting each other`s sovereignty and territorial boundaries.

Option 4, "Non-interference in internal affairs," is another Panch Sheel principle. It advocates for respecting the internal affairs of other countries and not interfering in their domestic matters.

Therefore, the correct answer is option 3, as nuclear deterrence was not a part of the Panch Sheel principles.