The edge of each cube used to build this rectangular prism is 1/3 inch long. Based on the drawing, the rectangular prism has 2 3x3 boxes.
Each small box has a dimension of 1/3 in all sides.
So the equation that shows the volume of the prism in cubic inches is choice 2
Volume = (3/3 * 2/3 * 3/3)
Volume = 2/3 in^3