Answer:
Caste System is the right answer.
Explanation:
The 10th Mandala of Rig Veda mentions the Varna or Caste system. This is the main scripture of the Aryans. During the Rig Vedic period, the caste system was flexible, however, during the later Vedic age, it became rigid. In this system, the Brahmans and Kshatriyas became dominant and made the Vaishyas to pay taxes and Shudras to serve them.