the box is considered a prism
any prism the formula for volume is V=area of the base times height so
the first two boxes have the base of 16 plus the height of 3
so 16*3=48
48*2=96
the other box has the height of 5 so
16*5=80
in total they want the volume of all boxes so
96+80=176
answers B:)
if you need to elaborate lmk