The Oxidation of Iron to Rust Is a Problem Structural

Multiple Choice

The oxidation of iron to rust is a problem structural engineers need to be concerned about,but the oxidation of aluminum to aluminum oxide is not so much of a problem.Why?

A) Since aluminum is so light and inexpensive,it is easily replaced when corroded.
B) Aluminum oxide is insoluble in water and thus forms a protective coating that prevents continued oxidation of the aluminum.
C) Aluminum oxide is even stronger than aluminum.
D) The oxidation of aluminum is a very slow reaction,taking hundreds of years before any structural changes are noticed.