He is in the room ____ clean the room.("that" or "where")

He is in the room ____ clean the room.("that" or "where")
He is in the room ____ clean the room.("that" or "where")

He is in the room ____ clean the room.("that" or "where")
where 前面不是说了in the room 嘛

( where )= in + which