Read this letter written by US General Ulysses S. Grant. Which sentences most clearly indicate that the writing style is informal and that this is a personal letter?

A.All I can say is that I am well

BMy position is naturally strong and fortified against an attack from outside.

c.I do not look upon the fall of Vicksburg as in the least doubtful

D.The fall of Vicksburg now will only result in the opening of the Mississippi River and demoralization of the enemy.