The priesthood, a specialized occupation in a person takes charge full-time of a large religious organization, first developed in which type of societies?

I believe the answer is: Agrarian

A society could be said to has a specialized occupation if there is a clear division of labor that differentiate the duty/job description between one citizen and another.
This division of labor was first created by agrarian society when they separate their workforce to handle different parts of farming process.

1.  go out into nature and commune with the divine2.  experience real solitude to truly perceive nature3.  realize that individuals are meant to learn from nature and transcend it4.  think of nature as a symbol of the divine