问题：

[单选] A vessel is constructed with a steel hull and an aluminum superstructure. Which statement is TRUE?（）

A . The aluminum will provide greater resistance to the spread of fire by conduction
B . The aluminum structure is usually attached to a steel coaming by a method that insulates the two metals
C . If the superstructure is stressed，an aluminum structure requires additional expansion joints to prevent fracture
D . The steel at the area of the aluminum-to-steel connection must be closely checked for galvanic corrosio