How old are you? There is only one answer to this. 
The answer to this is how old you are. Not someone else. The question is not about someone else. 
The question is about that one. The question is “How old is that?” How old is that one? 
There is only one answer to that question. The question is not open-ended. There is one answer. 
Answer it. With any kind of answer.

- [Anonymous]