The correct answer is: a) Shakti worship traditions.
Shakti is a Hindu goddess who is associated with power, fertility, and creation. She is often depicted as a mother goddess, and her worship is often associated with animal sacrifice. In ancient Assam, Shakti worship was a major religion, and animal sacrifice was a common practice.
Tribal customs are also a possible explanation for the practice of animal sacrifice in ancient Assam. Many tribal groups in Assam practice animal sacrifice, and it is often seen as a way to appease the gods or to ensure good luck. However, there is no evidence to suggest that tribal customs were the primary reason for animal sacrifice in ancient Assam.
Buddhist rituals are another possible explanation, but they are less likely than Shakti worship or tribal customs. Buddhism does not typically involve animal sacrifice, and there is no evidence to suggest that it was practiced in ancient Assam.
Vedic practices are the least likely explanation. The Vedas are a collection of ancient Hindu texts, and they do not mention animal sacrifice. In fact, the Vedas often condemn the practice of animal sacrifice.
Therefore, the most likely explanation for the practice of animal sacrifice in ancient Assam is that it was linked to Shakti worship traditions.