Why is the caste system a central part of the hindu religion?

there are different hindu gods for each caste level.
it is a carryover from hinduism’s roots in the aryan migration.
it correlates to differing levels of spirituality.
hinduism states that actions are judged according to caste level.

lee and grant, both of whom held the highest rank in their respective armies, had known each other slightly during the mexican-american war (1846-48) and began their dialogue by exchanging awkward personal inquiries. characteristically, grant had arrived in his mud-splattered field uniform while lee had turned out in full dress attire, complete with sash and sword.

explanation: