Translation:Is it a bottle?
병 can also be translated as illness or disease. If the answer is "Is it a bottle?", "Is it an illness?" should not be marked as incorrect.
That's because Koreans have stopped using Hanja. This sentence, technically, can be rewritten as "瓶이니" or "病이니". Both answer should be accepted. By the way, we may use "疾病"(질병) to avoid confusion.