A carpenter plans to extend the length of a desk by \( 7 \) teet. Let \( x \) represent the desk's original length. The expression \( 9 ( x + 7 ) \) represents the area of the desk's surface, where \( 9 \) is the width, in feet, and \( ( x + 7 ) \) represent the extended length in feet, of the desk. The carpenter thinks that the area of the extended portion of the desk is \( 16 \) square leet. Which choice below includes the expanded lorm of the area expression for the desk's surface and the correct area of the extended portion of the desk's surface?
\( 9 x + 7 \) and \( 7 \) square feet
\(9 x + 63 \) and \( 9 x \) square feet
\( 10 x + 16 \) and \( 10 x \) square feet
\( 9 x + 63 \) and \( 63 \) square feet