Please consider the complete question.
A prism has a length of 9 millimeters, height of 3 and one-half millimeters, and width of 8 and one-half millimeters. What is the volume of the rectangular prism?
We know that volume of rectangular prism is product of its length, width and height.
Let us convert our given mixed fraction into decimal.
Therefore, the volume of the given prism would be
and option D is the correct choice.