- Assertion (A) is true. The Planning Commission played a central role in deciding economic priorities, allocating resources, and coordinating development activities across the Union and States, thus exercising significant influence akin to an 'economic cabinet'. - Reason (R) is true. A core function of the Planning Commission was to formulate Five Year Plans, which inherently involved planning for the effective and balanced utilization of various resources, including natural resources. - Reason (R) provides the primary mechanism through which the Planning Commission exerted its influence and became known as the 'economic cabinet'. The formulation of comprehensive national plans, including resource allocation, was the basis of its powerful role across different levels of government. Therefore, (R) is a correct explanation of (A).