Step 1: Understanding the Concept:
Judicial review is the power of the judiciary to examine the constitutionality of legislative acts and executive orders.
Step 2: Detailed Explanation:
- Assertion A is correct: In various cases like Kesavananda Bharati and Minerva Mills, the SC held that judicial review is an unalterable feature of the Basic Structure.
- Reason R is correct: The purpose of this power is to act as a check on other branches and safeguard fundamental rights.
Because the judiciary's role as the protector of the constitution and rights (as stated in R) is fundamental to the constitutional scheme, it is considered part of the basic structure (as stated in A).
Step 3: Final Answer:
Both are correct and R explains A.