Some of the tenth-century stave churches of Norway are still standing, demonstrating that with sound design and maintenance, wooden buildings can last indefinitely.
(A) standing, demonstrating that with sound design and maintenance, wooden buildings can last indefinitely
(B) standing, demonstrating how wooden buildings, when they have sound design and maintenance, can last indefinitely
(C) standing; they demonstrate if a wooden building has sound design and maintenance it can last indefinitely
(D) standing, and they demonstrate wooden buildings can last indefinitely when there is sound design and maintenance
(E) standing, and they demonstrate how a wooden building can last indefinitely when it has sound design and maintenance