How can the ketone in a β-ketoester be protected during hydride reduction?

[![Reaction scheme](https://i.stack.imgur.com/uqtLx.png)](https://i.stack.imgur.com/uqtLx.png)


I am supposed to find what **X** is. I know that $\ce{LiAlH\_4}$ will convert all carbonyl groups to alcohols, and the ester group is being reduced. The only way of ending up with a ketone that I can think of is by a pinacol reaction.


However, the answer given was that **X** was $\ce{HOCH2CH2OH + H+}$. How does this work?


