Why was the day after Thanksgiving originally called 'Black Friday' in the retail industry?

Black Friday has become one of the biggest shopping festivals worldwide, marking the beginning of the holiday shopping season. But do you know how this retail phenomenon got its name? Test your knowledge about the origins of this massive shopping event that retailers prepare for all year and that significantly impacts quarterly earnings for many businesses.

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Because retailers traditionally moved from operating at a loss ('in the red') to making a profit ('in the black') on this day
Due to the chaos and traffic congestion that occurred in Philadelphia when suburban shoppers and tourists flooded the city before the Army-Navy football game
Because it marked the day when retail employees called in 'black' (sick) after Thanksgiving celebrations, leading to staffing shortages
It originated from a stock market crash that occurred on a Friday after Thanksgiving in the 1950s, affecting retail stocks