The correct order is:
3. A system of social classes based on birth evolved;
1. Castes are rigid and inflexible; people are born into a caste and cannot leave it;
4. Castes are a prominent part of people's lives, but people may have been able to move around;
2. Discrimination based on caste is determined to be illegal;
The caste system is a system with very long history, and it has been part of the Indian culture for centuries. At the begging, when it was implemented into the society, the caste system was very rigid and strict, and people were destined from birth to a certain social status for the rest of their lives. This lasted for a very long period of time. In the past century, the caste system started to be a bit more flexible, so certain individuals that showed greater qualities were able to progress into the caste system. And recently, the caste system, and discrimination based on it, have been made illegal in the country, so officially it has come to an end.
