Why does bierce use a flashback in section 2 of "an occurrence at owl creek bridge" instead of proceeding with the events taking place?

to introduce peyton farquhar
to emphasize the folly of romanticism
to depict the cunningness of the federal soldiers
to emphasize the naivety of the confederacy
to the reader know what led to the events in section 1
a.
1, 2, 3
b.
3, 4, 5
c.
1, 2, 5
d.
2, 3, 5
e.
1, 4, 5