Question

Which statement from FDR's speeches uses parallel structure?

Answer 1

American ships have been sunk; American airplanes have been destroyed. (Apex)

Answer 2

I'd say that the statement from FDR's speeches that uses parallel structure is C. American ships have been sunk; American airplanes have been destroyed.
Both of these independent clauses use the passive form of the verb - in the first clause, the passive form of the verb to sink is used, and in the second, of the verb to destroy.
A parallel structure means that throughout a sentence, the same form of words is used, and given that here both sentences have passive forms, I'd say C is the correct answer.