The correct option is 1 and 3 only.
Explanation
The Khajuraho group of temples, built by the Chandela dynasty between 950 and 1050 AD in Madhya Pradesh, represents the zenith of the Nagara style of temple architecture in Central India.
Statement 1 is Correct: The temples at Khajuraho, such as the Lakshmana Temple, are constructed on a high platform known as the Jagati. This platform is accessed by stairs and serves to elevate the sacred structure above the surrounding ground level, a distinctive feature of this school.
Statement 2 is Incorrect: The erotic sculptures (Mithuna figures) are primarily placed on the exterior walls (Jangha) and the intermediate spaces between the assembly halls. The interior of the sanctum sanctorum (Garbhagriha) is comparatively austere and spiritual, housing the main deity, and does not feature these erotic depictions.
Statement 3 is Correct: The temples are predominantly made of sandstone (with granite used in a few earlier ones) and belong to the Nagara style. They exhibit characteristic features such as the curvilinear tower (Shikhara) topped with an Amalaka and Kalasha, and the Panchayatana layout.
Key Takeaway: Khajuraho temples (Chandela School) are defined by their high platforms (Jagati), sandstone construction, Nagara architecture, and the placement of erotic sculptures on the exterior rather than inside the sanctum.