Given below are two statements, one labeled as Assertion (A) and the other labeled as Reason (R):

Assertion (A): Ellora's famous Kailashnath shrine represents a remarkable monolithic architectural feat.
Reason (R): The entire temple complex was sculpted by excavating a single solid basalt cliff downwards from its peak.

In light of the statements above, choose the correct answer from the options given below:

The correct answer is Both Statement A and Statement R are correct, and Statement R provides the valid explanation for Statement A.

Analysis of Assertion (A):
Assertion (A) states that Ellora's famous Kailashnath shrine (Cave 16) represents a remarkable monolithic architectural feat. This statement is entirely true. The Kailashnath Temple at Ellora, Maharashtra, built during the Rashtrakuta dynasty (primarily under King Krishna I in the 8th century), is world-renowned as one of the largest single monolithic rock-cut structures in existence.

Analysis of Reason (R):
Reason (R) states that the entire temple complex was sculpted by excavating a single solid basalt cliff downwards from its peak. This statement is also entirely true and accurately explains why the shrine is considered such a monumental monolithic feat. Unlike traditional architecture built from the ground up using assembled stones, the artisans excavated top-down (top-to-bottom) out of a single continuous basalt rock hill, carving out detailed halls, pillars, and sculptures without using separate building blocks.

Conclusion:
Since the top-down excavation of a single basalt cliff (Reason R) directly explains why and how the temple is a monolithic architectural masterpiece (Assertion A), Reason (R) is the correct and valid explanation for Assertion (A).