Which phrase from the gettysburg address encourages feelings of responsibility to continue fighting for a cause so many people have died for?
a. that these dead shall not have died in vain
b. we cannot hallow this ground
c. we have come to dedicate a portion of that field
d. shall not perish from the earth

I believe that the letter A encourages the feeling to keep fighting as it implies that if the people were to lose their morale and stop supporting the fight, then everyone who died during the battle will have failed at unifying the United States. By stating that the continuation of fighting will mean that the dead did not die in vain, it gives the responsibility of honouring the fallen to the soldiers and citizens of the US.