The action of the chapter followed what pattern for the soldiers who stayed and fought?

Okay, I'm going to go with A here just because of the details;

Thee chapter begins with the youth waking up; thus, he's had a reprieve.

"The youth awakened slowly. He came gradually back to a position from which he could regard himself. For moments he had been scrutinizing his person in a dazed way as if he had never before seen himself."

Second, they believe the fighting to be over, but it wasn't; this was the reaction;

"To the youth it was an onslaught of redoubtable dragons. He became like the man who lost his legs at the approach of the red and green monster. He waited in a sort of a horrified, listening attitude. He seemed to shut his eyes and wait to be gobbled.

A man near him who up to this time had been working feverishly at his rifle suddenly stopped and ran with howls. A lad whose face had borne an expression of exalted courage, the majesty of he who dares give his life, was, at an instant, smitten abject. He blanched like one who has come to the edge of a cliff at midnight and is suddenly made aware. There was a revelation. He, too, threw down his gun and fled. There was no shame in his face. He ran like a rabbit.

Others began to scamper away through the smoke. The youth turned his head, shaken from his trance by this movement as if the regiment was leaving him behind. He saw the few fleeting forms.

He yelled then with fright and swung about. For a moment, in the great clamor, he was like a proverbial chicken. He lost the direction of safety. Destruction threatened him from all points.

Directly he began to speed toward the rear in great leaps. His rifle and cap were gone. His unbuttoned coat bulged in the wind. The flap of his cartridge box bobbed wildly, and his canteen, by its slender cord, swung out behind. On his face was all the horror of those things which he imagined.

The lieutenant sprang forward bawling. The youth saw his features wrathfully red, and saw him make a dab with his sword. His one thought of the incident was that the lieutenant was a peculiar creature to feel interested in such matters upon this occasion.

He ran like a blind man. Two or three times he fell down. Once he knocked his shoulder so heavily against a tree that he went headlong."

Lastly, their reliefs had arrived and the tides had turned;

"As another officer sped his horse after the first messenger, the general beamed upon the earth like a sun. In his eyes was a desire to chant a paean. He kept repeating, "They 've held 'em, by heavens!""

"The youth cringed as if discovered in a crime. By heavens, they had won after all! The imbecile line had remained and become victors. He could hear cheering."