Answer: D. The people must not give up; they must win the war for those who have died for the cause
Explanation:
The last sentence is as follows:
"It is rather for us to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that 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."
Even though it is indeed a very long sentence, what is basically states is that they must not give up the fight. If other people have died for a certain cause before it was accomplished, the only way for them to not have died in vain is if people keep on fighting.
