Question

what did lincoln allow for in this part of the emancipation proclamation?
freed enslaved people could work as mechanics.
freed enslaved people could join the military
confederate soldiers could join the union.
and i further declare and make known, that such persons freed enslaved people of suitable condition, will be received into the armed service of the united states.

Explanation:

The Emancipation Proclamation excerpt says freed enslaved people of suitable condition would be received into the armed service of the US. The option "Freed enslaved people could join the military" matches this as joining the armed service is military service. The other options: "Freed enslaved people could work as mechanics" is too narrow (the proclamation was about armed service, not just mechanics), and "Confederate soldiers could join the Union" is incorrect as the proclamation was about freed enslaved people, not Confederate soldiers.

Answer:

Freed enslaved people could join the military