Explanation:

- Option 1: A marriage ritual

"AshtaPada" does not refer to a marriage ritual. Ancient India had numerous unique rituals, but AshtaPada wasn't one of them in this context.

- Option 2: An Asura with eight legs

In Indian mythology, Asuras are often depicted as powerful beings, but there's no prominent record of an Asura specifically called "AshtaPada."

- Option 3: Game of chess

"AshtaPada" in ancient India is indeed linked to a board game, considered a precursor to modern chess. The term refers to the board with 64 squares used in traditional games.

- Option 4: Cavalry unit comprising of eight horses

This doesn't match historical references to AshtaPada in ancient Indian texts.