The question uses the term "right" in the form of a question. We can substitute the word "right" with the expression "is that correct", so the only correct answer to the question would have to be a "yes or no" response. So, A is the correct answer. Unfortunately, the rest of the sentence in A is not related to the question, i.e., it's extra, unnecessary information, so that is why the answer does not look correct, but it does answer the question, using the word "yes".
Perhaps, the use of the word "cage" is similar to the use of the word garage (place where we park a car).