While going through some problems as part of self-study I encountered the following True/False question:
Q. Steven only consumes two goods: $X$ and $Y$. If $X$ is a Giffen good for Steven, then $Y$ must be a normal good for Steven.
The given answer is True.
I am unable to understand why it is necessary for the other good to be normal. Why can't it be inferior/Giffen?