[单项选择]Acme Nutrition manufactures a wide variety of vitamin supplements. It has a single manufacturing facility with 3 regional warehouses and 16 district sales offices. Currently the manufacturing facilityrequires 210 IP addresses； each warehouse requires 51 IP addresses； each district sales officerequires 11 IP addresses； and the IP WAN requires 38 IP addresses. if Acme Nutrition plans for20 percent growth in facilities， how many Class C subnets will the district sales offices require？（）
A.  19 （3 from the warehouse range and 16 from a separate Class C address）
B.  19 （3 from the warehouse block， 15 from a separate Class C block and 1 from the IP WAN block）
C.  20 （4 from the warehouse range，15 from a separate Class C block and 1 from the IP WAN block）
D.  16 （3 from the warehouse range and 13 from a separate Class C address）