The Great Stupa at Sanchi is one of the oldest and most important Buddhist monuments in India. It is renowned for its four elaborately carved gateways, known as Toranas, located at the four cardinal directions (North, South, East, West) providing access to the circumambulatory path around the stupa.
Symbolic significance of the Toranas at Sanchi Stupa:
(Ŕ) Gateways to a sacred space: The Toranas serve as ceremonial and symbolic entrances into the sacred precinct of the stupa. Passing through a Torana signifies entering a realm of spiritual significance.
(ŕ) Representation of Buddhist teachings and cosmology: The intricate carvings on the Toranas depict various scenes, symbols, and narratives related to Buddhism. These include:
(Ŗ) Jataka tales: Stories of the Buddha's previous lives (bodhisattva incarnations). (Relates to option b, but this is one aspect of what they depict, not their sole or primary symbolic significance as "gateways").
(ŗ) Events from the life of the historical Buddha (Siddhartha Gautama): Though often represented aniconically (by symbols like the Bodhi tree, wheel, footprints, empty throne) in early Buddhist art like at Sanchi.
(Ř) Buddhist symbols: Such as the Dharma Chakra (Wheel of Law), triratna (Three Jewels: Buddha, Dharma, Sangha), stupas, Bodhi tree, elephants, lions, yakshas/yakshis (nature spirits).
(ř) Patronage scenes: Depictions of devotees, royal patrons (like Ashoka, though his direct commemoration isn't the *primary* function of the torana's symbolism itself).
(Ś) Symbolic transition: They mark a transition from the mundane, secular world outside to the sacred, spiritual space within the stupa complex.
Considering the options:
(ś) (a) They represent the gateway to the divine realm and the Buddha's teachings: This captures the overarching symbolic function of the Toranas as highly significant ceremonial entrances into a sacred Buddhist space, a space where one engages with the Dharma (teachings). The carvings on them further elaborate on these teachings.
(Ŝ) (b) They depict scenes from the Buddha's past lives and guide visitors towards enlightenment: While they do depict Jataka tales (past lives) among other scenes, and their overall purpose is to inspire and guide, option (a) describes their fundamental role as symbolic "gateways" more comprehensively.
(ŝ) (c) They serve as structural supports for the stupa's dome and enhance its stability: Toranas are freestanding gateways, separate from the main stupa structure (which consists of the anda or dome, harmika, yashti, chhatra). They are not primary structural supports for the dome.
(Ş) (d) They commemorate the life and achievements of Emperor Ashoka, the stupa's patron: While Ashoka was a great patron of Buddhism and initiated the construction of the original stupa at Sanchi (later enlarged), and some inscriptions might refer to patronage, the Toranas themselves (built later by Satavahana patrons) are primarily symbolic religious gateways richly carved with Buddhist narratives and symbols, not solely monuments to Ashoka.
Option (a) best describes the primary symbolic significance of the Toranas as gateways to the sacred realm and conduits for understanding Buddhist teachings through their iconography.
\[ \boxed{\text{They represent the gateway to the divine realm and the Buddha's teachings}} \]