Q. Which three sacred texts of Ancient India are termed "Prasthan Trayi"?      RAS(Mains)-2018    Paper-1  #RAS #UDAIPUR #RAS_Mains

Prasthanatrayi (प्रस्थानत्रयी), literally, three sources (or axioms), refers to the three canonical texts of theology having epistemic authority, especially of the Vedanta schools. It consists of:

1. The Upanishads, known as Upadesha prasthana(injunctive texts), and the Śruti prasthāna (the starting point or axiom of revelation), especially the Principal Upanishads. 
2. The  Brahma Sutras, known as Sutra prasthanaor Nyaya prasthana or Yukti prasthana (logical text or axiom of logic)
3. The  Bhagavad Gita, known as Sadhana prasthana(practical text), and the Smriti prasthāna (the starting point or axiom of remembered tradition)