（）使用固定车厢式矿车、翻转车厢式矿车、底卸式矿车、材料车和平板车等运送人员。

A、可以

B、严禁

C、不可以

D、必须

Language is said to be arbitrary because there is no logical connection between （）and meanings.

A.sense

B.sounds

C.objects

D.ideas