The correct option is Karla.
Explanation
Rock-cut architecture in Western India reached its zenith under the patronage of the Satavahanas and Western Kshatrapas. These excavations are primarily divided into Chaityas (prayer halls) and Viharas (residential halls). Among the surviving examples, the Chaitya hall at Karla represents the culmination of the early phase of Hinayana rock-cut architecture.
Detailed Analysis:
- Karla (Option a): Located near Lonavala in Maharashtra, the Great Chaitya at Karla (Cave 8) is the largest and most completely preserved rock-cut Chaitya hall in India. Excavated during the 1st century CE, it measures approximately 37.8 meters in depth, 13.7 meters in width, and 14 meters in height. It is renowned for its massive proportions, the presence of original wooden ribs in the vaulted roof, and elaborate pillars featuring lion capitals.
- Ajanta (Option b): While Ajanta contains significant Chaitya halls (such as Caves 9, 10, 19, and 26) known for their exquisite paintings and sculptures, they are not as architecturally extensive in scale as the single Great Chaitya at Karla.
- Nashik (Option c): The Pandav Leni caves at Nashik include Chaitya halls (e.g., Cave 18), but these are smaller and less architecturally complex compared to the grandeur of Karla.
- Ellora (Option d): Ellora features the Vishvakarma Cave (Cave 10), which is a significant Chaitya hall. However, it belongs to a much later period (approx. 7th century CE) and differs in style. In terms of the classic definition of the "most extensive" early rock-cut Chaitya, Karla holds the distinction.
Key Takeaway:
The Great Chaitya at Karla is the largest rock-cut prayer hall in India, distinguished by its vaulted roof with original wooden ribbing and a grand sun-window (Chaitya arch).