Payment with 1-yuan notes

A woman used five boxes of one-yuan notes, totaling about 100,000 yuan to pay for a car at a BMW dealership in Zhengzhou, Henan province. The bills weighed more than 100 kilograms. A dozen workers counted the money from 9 am until 3 pm. She paid the rest of the money by credit card. It is not known why she used the small bills to pay for the car.

How many hours did the workers need to count the money?

A. Five hours

B. Six hours

C. Seven hours

（中国日报网英语点津 Helen 编辑）