Rock Adventures has 15 employees each working 40 hours per week and earning $30 an hour. Federal income taxes are withheld at 15% and state income taxes at 6%. FICA taxes are 7.65% and unemployment taxes are 3.8% of the first $7,000 earned per employee. What is the employer's total payroll tax expense for the first week of January?
A) $5,157.
B) $12,843.
C) $13,923.
D) $18,000.