The surface area of a rectangular prism (S) is given in terms of length L, width W, and height H by
.. S = 2(LW +H(L +W))
If you double the height, now you have new surface area S'
.. S' = 2(LW +2H(L +W)) = 2(LW +H(L +W)) +2H(L +W)
.. = S +2H(L +W)
This is larger than the original surface area S, but is not as much as 2S.
Selection C is appropriate.
