小张高中毕业之后，去上了四年大学；如果他当时没有上大学，而是去上班，四年下来，他能够获得的劳动报酬大概为7.5万元，则小张的（）是7.5万元。

A.上大学的成本 

B.不上大学的成本 

C.上大学的机会成本 

D.上大学的心理成本

On a ship，a cabinet or space containing the controls or valves for the fixed firefighting system must be（）.

A.posted with instructions on the operation of the system

B.ventilated and equipped with explosion-proof switches

C.painted with red and black diagonal stripes

D.equipped with a battery powered source of emergency lighting