Salesperson A’s compensation for any week is $360 plus 6 percent of the portion of A’s total sales above $1,000 for that week. Salesperson B’s compensation for any week is 8 percent of B’s total sales for that week. For what amount of total weekly sales would both salespeople earn the same compensation ？（）
A．$21,000
B．$18,000
C．$15,000
D．$4,500
E．$4,000
