The correct option is D S1, S2 and S3
When compared to the Rig Vedic period, later Vedic period has more complex religious rituals and sacrifices. The Brahmanas became instrumental in performing various religious practices.This led to many people not able to afford or not able to understand the rituals. People started believing in charms and magic, birth and rebirth, concept of karma. Speculations on philosophical or spiritual subjects like God, universe, and rebirth gained preference in this period.