The correct option is A.
There are two basic sources which an author can draw from when writing an article. The first one is primary source and this refers to an account of an event or history by a person who actually witness the event or the person who experience the event directly. The second one is secondary source and it refers to those accounts of events that are drawn from primary sources.
Thus, a journal account about civil war by a civil war soldier who experienced the war is considered a primary source.