Which of the following is NOT a condition of a perfectly competitive market（）

A. Sellers make economic profits.

B. Firms face elastic demand curves.

C. Individual sellers each have a small share of the market.

秘密级涉密载体应当存放在（）中。

A、密码文件柜 

B、铁皮横 

C、密码保险柜 

D、一般木柜