A Piece of Tin $y = 16$ Inches on a Side, Is to Have Four Equal Squares

Multiple Choice

A piece of tin, $y = 16$ inches on a side, is to have four equal squares cut from its corners, as in the illustration. If the edges are then to be folded up to make a box with a floor area of 16 square inches, find the depth of the box.

A) 11 in
B) 13 in
C) 6 in
D) 12 in
E) 9 in