The answer is b) Estate stratification.
This stratification system was a long-run result of feudalism since it fell under the same principles:
1) There's a social hierarchy in which there were a noble class and a peasant class.
2) Only the noble class could have land ownership, and the peasant (or serf) class must work it for the noble's usufruct.
This system of stratification was upheld not only by illustrated monarchies but also by modern nation-estates (like the U.S.), this is how it received the name of estate stratification.
