Niceeeeeeeeeeeeeeee :) :)
Answer:
Birth
Explanation:
Traditionally, a person's caste is determined at birth and channels them into that caste's occupation.
1= i
2= ii
3= ii
4= iv
5= v
6= vi
7= vii
8= viii
9= ix
10= x
It would be an "effective secondary source document" that best describes a chart developed 20 years after a historical event, since the information as had time to "settle"--although of course this doesn't automatically mean that the chart is "effective". hope this helps :)