A grocer is storing small cereal boxes in large cartons that measure 25 inches by 42 inches by 60 inches. If the measurement of each small cereal box is 7 inches by 6 inches by 5 inches, then what is the maximum number of small cereal boxes that can be placed in each large carton ？（）

A．25

B．210

C．252

D．300

E．420

一个跨距内一根回流线的接头不得超过（）

A、0个

B、1个

C、2个

D、根据跨长度而定