We need to convert the following to reported speech:

Why have you taken a room on the tenth floor?

I am confused about the word order.

Should it be

He asked her why she had taken a room on the tenth floor.

or

He asked her why had she taken a room on the tenth floor.

or neither? Why?

I suppose since we convert an interrogative sentence into a declarative one (on conversion to reported speech), the correct one would be the first. However, the it doesn't 'sound' right. And English is not lacking in exceptions.