Hannah is writing an essay about the human errors that were made during the Chicago fire of 1871.

Several key human errors contributed to the spread of the Chicago fire of 1871. When the blaze first began, Bruno Goll refused to sound the first alarm, which was housed in his drugstore. Later, at the courthouse, Mathias Schaffer instructed his assistant, William J. Brown, to sound Box 342 instead of Box 319, sending firefighters toward the wrong location. When Schaffer realized his mistake, Brown flat-out refused to strike the correct box. Even after the fire, Brown was confident in his decision not to correct the mistake. Finally, as the blaze raged on, fireman John Dorsey attempted to sound a special alarm, but accidentally sounded a general alarm. This meant that additional trucks and equipment were not immediately sent out to help.

Which is one extraneous detail from this passage?

“Several key human errors contributed to the spread of the Chicago fire of 1871.”
“Finally, as the blaze raged on, fireman John Dorsey attempted to sound a special alarm, but accidentally sounded a general alarm.”
“Even after the fire, Brown was confident in his decision not to correct the mistake.”
“When Schaffer realized his mistake, Brown flat-out refused to strike the correct box.”