The correct answer is option 3 - Kesavananda Bharati case.

The `Basic Structure Doctrine` refers to the constitutional principle that certain fundamental features of the Indian Constitution cannot be altered by the Parliament through its amending power. It means that there are certain core principles and values that form the foundation of the Constitution and cannot be changed or destroyed.

The Supreme Court of India enunciated the Basic Structure Doctrine in the Kesavananda Bharati case in 1973. This landmark case involved a challenge to the constitutional validity of the 24th amendment, which sought to curtail the power of the judiciary to review the constitutional amendments. The Supreme Court, in its judgment, held that while the Parliament has the power to amend the Constitution, it does not have the power to destroy or alter its basic structure.

The Basic Structure Doctrine has been instrumental in ensuring the sanctity and stability of the Indian Constitution. It protects the fundamental rights of the citizens, the federal structure of the government, and the democratic principles enshrined in the Constitution. The doctrine acts as a safeguard against potential abuse of power by the Parliament and upholds the supremacy of the Constitution.