What is the proper use of dashes within a sentence to set apart something surprising?

What element of dante's inferno shows the reader that he wants to expose corruption in the church? a. by placing many church leaders among the sinners in hell b. by changing his own personality to create the dante character c. by allowing virgil, a well-respected poet, to be his guide d. by setting his story in hell and following the biblical description of hell2b2t