Which sentence from "the gettysburg address" most effectively develops the theme that it is important to honor those who have fallen in defense of our country’s principles?

"now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and dedicated, can long endure."

"we are met on a great battle-field of that war."

"but, in a larger sense, we can not dedicate—we can not consecrate—we can not hallow—this ground."

"we have come to dedicate a portion of that field, as a final resting place for those who here gave their lives that that nation might live."