(A) ** strengthen their support for the Union cause.
(B) seek revenge on those who killed the brave, proud soldiers.
(C) finish the work of freeing all people who are held in bondage.
(D) dedicate a portion of the field as a final resting place.
EXPLANATIONS BELOW
Concept note-1: -What this quote is saying is by continuing the fight the audience would insure the deaths of those who died in battle would not be in vain. If they gave up on the cause of the war, then those who died would have died for a lost cause making their deaths in vain.
Concept note-2: -Gettysburg Address …we here highly resolve that these dead shall not have died in vain-that this nation, under God, shall have a new birth of freedom-and that government of the people, by the people, for the people, shall not perish from the earth. Abraham Lincoln, Gettysburg Address, November 19, 1863.