Question

What was used to justify the caste system?

Answer 1

One of things that was used to justify the caste system was "aryan supremacy", since many of the people who were at the "bottom end" of the system were subjugated to racist policies. 

Answer 2

Hey Bud, your answer is The Rig Veda, Ive tried all three from them but got all incorrect except from rig veda. Hope this helps :)