Answer: A.) curable external obsolescence.
Explanation: According to wikkipedia obsolescence is" the state of being which occurs when an object, service, or practice is no longer wanted even though it may still be in good working order."
An ornate design is well crafted design that can hardly be reproduced. Due to the activity of pollution the very creative design is badly damaged, and although the building is in good working shape it is not very desirable to stay in due to its ugly appearance.