The majority of students who attended secondary schools came from
a. middle-class families
b. the countryside
c. peasant families
d. czarist russia

A. Middle class families-- middle class families could financially support children going to school. 

Continuing in education beyond primary school requires the family to be able to continue to support a child into their teenage years. Middle class families had enough money to support their children's education instead of needing the child to get a job or be married to start their new home.