The correct option is 2 and 3 only.
Explanation
The Mahabodhi Temple at Bodhgaya is a UNESCO World Heritage Site and one of the earliest surviving examples of monumental brick architecture in India. While the original shrine was built by Emperor Ashoka, the current structure dates back to the Gupta period (5th-6th century CE) and later.
Statement 1 is Incorrect: The Mahabodhi Temple is constructed primarily of brick, not granite. It is historically significant for being one of the oldest standing brick temples in eastern India. While stone was used for the railings and toranas, the main temple structure is a masterpiece of brickwork.
Statement 2 is Correct: The design of the temple is unique and does not strictly adhere to the classical Nagara (curvilinear shikhara) or Dravida (stepped pyramidal vimana) styles, which fully developed later. It features a straight-edged, high pyramidal tower (shikhara) surmounted by an amalaka, representing an early stage in the evolution of Indian temple architecture.
Statement 3 is Correct: The temple suffered significant damage and neglect over centuries. The structure standing today is largely the result of extensive reconstruction and restoration carried out in the late 19th century (1880s) during the Colonial Period. This restoration was led by Sir Alexander Cunningham and J.D. Beglar, who rebuilt the temple based on the structural remains of the 7th-century design and miniature models found at the site.
Key Takeaway: The Mahabodhi Temple is a seminal example of Gupta-era brick architecture, distinguished by its unique straight-edged shikhara, and owes its current form to major 19th-century British restorations.