Based on its prefix which is the correct definition of impersonal

"Im" means "not". So, here it means 'not personal'.

Explanation: "Im" prefix is used to deny or nullify the meaning of the former word and here, as per the definition "im" is denying the meaning of the word 'personal'. To understand the meaning we can refer it to Eliot's "Impersonal theory of poetry" in "Tradition and the Individual Talent" where he is approaching a thought to the poet which is negating his(poet's) presence from the work. He says that the poet should act as a catalyst while writing a work and his/her work should not contain any personal traits of him/her or "Impersonal".  

which of the following was specifically permitted by the emancipation proclamation?

free african americans were allowed to fight for the confederacy.

free african americans were allowed to enlist in the union army and navy.

enslaved people in border states were allowed to move to the north.

enslaved people in border states were allowed to become confederate citizens.