使用下列哪个流格式控制符可以设置转换基数为十六进制（）。

A．dec

B．oct

C．hex

D．endl

A merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrators and sold each of the others for $5 more than the average (arithmetic mean) cost of the X calculators. If the total revenue from the sale of the calculators was $120 more than the cost of the shipment, how many calculators were in the shipment ？（）

A．24

B．25

C．26

D．28

E．30