Generally,how Were the Candidates for the Civil Service Examinations Chosen

Generally,how were the candidates for the civil service examinations chosen?

A) Half came from the farmer class.
B) Anyone in a local area could register for the examination.
C) Females were allowed to apply, but were never found qualified to actually take the examination.
D) Successful exam candidates came from a small core group from Kaifeng.
E) Never being completely fair, favoritism was given to powerful families.