Explanation: The question refers to which Article was defended by Dr. B R Ambedkar under the assumption that it would be used as `a matter of last resort`.

Option 1: Article 352 pertains to the proclamation of Emergency due to war or external aggression or armed rebellion. Dr. Ambedkar didn`t specifically associate it with the `last resort` concept.

Option 2: Article 359 allows the President to suspend the right to move any court for the enforcement of Fundamental Rights during a national emergency. This too, wasn`t connected with the last resort concept by Ambedkar.

Option 3: Article 356 states the provision for President`s rule in the Indian Constitution. Dr. Ambedkar defended this article stating it would be invoked sparingly and as a `last resort`. It was to ensure the governance of a state in case the constitutional machinery breaks down in that state.

Option 4: Article 368 holds the power of Parliament to amend the Constitution and its procedure. This too wasn`t linked by Dr. Ambedkar with `last resort`.

Hence, the correct answer is option 3 - Article 356, as it was the only article defended by Ambedkar as a matter of `last resort`.