Explanation: The correct option is 3. All three statements are correct.

1. The concept of Stupa is Buddhist in origin": Majority of the scholars associate the origin and significance of Stupas directly to Buddhism. While it's true that the architectural concept of raised mounds could predate Buddhism (possibly as burial mounds or tumuli), the specific religious and commemorative significance of Stupas is a development within Buddhist tradition.

2. Stupas were repositories of relics, primarily relics associated with the Buddha himself or other major figures in Buddhism. It typically contained the bodily remains of Buddhist monks or items of their use.

3. Yes, Stupas were built as a votive and commemorative structure. They were commissioned for a variety of reasons, such as to commemorate the spot where Buddha preached, or to commemorate a special event in his life, or as a monument sponsoring faith.

So, all statements fit within the general understanding of Stupas in the context of ancient Indian Buddhism. Hence, all three statements are correct.