The initial design and construction of which massive temple took place during the reign of Suryavarman II?

The massive temple whose initial design and construction occurred during the reign of Suryavarman II is Angkor Wat. Historical and architectural accounts attribute the commissioning and building of Angkor Wat to King Suryavarman II in the first half of the 12th century; the king’s reign (often dated c.1113–1150) oversaw the erection of this monumental Vaishnavite sanctuary [1]. Architectural descriptions identify Angkor Wat as a classical Khmer composition combining the temple‑mount and galleried plans, designed to represent Mount Meru, with characteristic features such as concentric galleries, a central quincunx of towers and a surrounding moat—traits dated to Suryavarman II’s period of construction in the 12th century [2]. Hence option 2 is correct.

Sources

1. [1] https://www.thehindu.com/features/metroplus/travel/reflections-from-the-kingdom-of-gods/article2562388.ece
2. [2] https://ignca.gov.in/invitations/Angkor_wat_booklet.pdf