Which of the following statements from What They Fought For shows the author's purpose was to persuade readers to believe his claim about why the northern soldiers fought;

A) Why did they persist through four years of the bloodiest conflict in American history, costing 360,000 northern lives-not to mention 260,000, southern lives and untold destruction of resources?

B) Puzzling over this question in 1863, Confederate War Department clerk John Jones wrote in his diary: "Our men must prevail in combat, or lose their property, country, freedom, everything....On the other hand the enemy, in yielding the contest, may retire into their own country, and possess everything they enjoyed before the war began.

C) Because, said northern soldiers, almost as if in echo of Abraham Lincoln, once we admit that a state can secede at will, republican government by majority rule will come to an end.

D) all of the above
(I already have an answer, but I want to be sure)