Which of the following are themes, or important ideas, of the "gettysburg address"? select all that apply (more than one answer is correct).

a) the sacrifices of the soldiers at gettysburg place a duty on the survivors to save the nation.

b) the union has reached a turning point in its struggle with the confederacy and is headed for victory.

c) it is up to the people of the united states, through devotion and sacrifice, to preserve democracy and freedom.

d) the civil war is being fought to preserve the same ideals of freedom and equality that inspired the american revolution.