The correct option is Semicircular chaitya arch.
Explanation
The Lomus Rishi cave, located in the Barabar Hills (Bihar), is a quintessential example of Mauryan rock-cut architecture. Dating back to the 3rd century BCE, these caves represent the earliest survival of rock-cut caves in India and are renowned for their translation of wooden architectural forms into stone.
Detailed Analysis
- Architectural Motif: The entrance facade of the Lomus Rishi cave is carved to imitate a wooden structure. The most prominent feature is the semicircular chaitya arch (often described as an ogee arch or horseshoe arch) with a finial at the top.
- Imitation of Timber: The arch replicates the bent timber supports used in contemporary wooden buildings. Beneath the arch, there is a carved lattice screen and a frieze of elephants approaching a stupa, further mimicking wooden craftsmanship.
- Comparison with other options:
- While the opening allows entry, the decorative motif defining the facade is the arch, not a simple rectangular doorway.
- A corbelled arch involves offsetting successive courses of stone or brick, a technique seen in the Indus Valley Civilization and early Islamic arches, but not in the monolithic carving of Lomus Rishi.
- A triangular pediment is a feature of Classical Greek and Roman architecture, not Mauryan rock-cut art.
Key Takeaway: The Lomus Rishi cave facade is the earliest surviving example of the chaitya arch in Indian architectural history, demonstrating the Mauryan technique of replicating timber construction in rock.