How did the Emancipation Proclamation change the war?

(1 point)
Responses

It increased the number of railroads to transport soldiers.
It increased the number of railroads to transport soldiers.

It provided an additional source of soldiers in the North.
It provided an additional source of soldiers in the North.

It gave the Northerners a cause to fight for.
It gave the Northerners a cause to fight for.

It freed all slaves in the United States.

It gave the Northerners a cause to fight for.