ANSWER: Keshvanand Bharati case
Explanation:
The basic structure doctrine is an Indian judicial principle that the Constitution of India has certain basic features that cannot be altered or destroyed through amendments by the parliament.Key among these "basic features", are the fundamental rights granted to individuals by the constitution. The doctrine thus forms the basis of a limited power of the Supreme Court to review and strike down constitutional amendments enacted by the Parliament which conflict with or seek to alter this "basic structure" of the Constitution. The basic structure doctrine applies only to constitutional amendments.