Read this description of the collapse of the Pemberton Mill in Lawrence, Massachusetts:

"In modern life and experience, there has been no near parallel to the catastrophe of Tuesday, January 10th, 1850, when this mill, in full operation, fell in a moment without warning, in an indescribable and utter ruin. On that memorable day, an observant citizen was walking on Canal Street at 4:45 o'clock p.m. As he stood before this modern mill, he saw it outlined against the winter sky, a perfect, complete, and symmetrical whole. Within its walls, six hundred and seventy people were working, each with his or her duties, hopes, and expectations. He had not gone six rods away when there was a roaring sound, a tremor of the earth, and a simultaneous crash. He turned and saw in place of the stately walls that stood but a moment before, perfect in every outline, only a mass of ruins, shapeless and huge, from which bewildered men and women were here and there escaping, some unhurt, some wounded and bleeding. The tidings flew like wildfire throughout the city, and without delay, a sturdy corps of volunteer mechanics and workers, of every occupation, covered the ruins, clearing away the debris and rescuing those confined therein. Just as the rescuers were reaching many of the imprisoned sufferers, there was a cry of alarm that appalled the stoutest hearts. A lantern containing burning fluid in the hands of a workman was broken by a chance blow from a pickaxe, wielded by another rescuer, and the ignited fluid fell among inflammable cotton and oily waste that burst into flames, unquenchable by means at hand. The huge pile was soon filled with a mass of flames, fed by saturated cotton, shattered timber, and crude waste."

Which statement is an example of causation?

A. Hundreds of people worked at the mill, and rescuers came to help.

B. News of the mill's collapse spread, and rescuers came to help the workers escape.

C. A man walked past the mill in the afternoon, and the mill caught fire.

D. The mill was in full operation and then collapsed.