please include work! i would like to understand. answer has to be one of multiple choice options. thank you :)

Smith Company sells its products at $820 per unit, net 30. The firm's gross margin ratio is 40 percent. The firm has estimated the following operating costs: Activity Cost Driver and Rate Sales calls $ 560 per visit Order processing $ 180 per order Deliveries $ 75 per order + $0.50 per mile Sales returns $ 90 per return and $3 restocking per unit returned Smith Company has gathered the following data pertaining to activities it performed for two of its customers: 26 660 NINTO 2 2,160 Number of orders Number of parts per order Sales returns Number of returns Number of units returned (per return) Number of sales calls Miles per delivery Shipping terms 4 40 13 10 FOB, Factory 10 50 9 20 TON, Destination What is Smith's total sales-sustaining cost applicable to XBT as a customer? What is Smith's total sales-sustaining cost applicable to XBT as a customer? Multiple Choice $4,200 $1,000. O $6,380. $6,500. $0