Akash's birthday cake is in the form of a 4×4×4 inch cube

Akash's birthday cake is in the form of a 4×4×4 inch cube

Akash's birthday cake is in the form of a 4×4×4 inch cube. The cake has icing on the top and the four side faces, and no icing on the bottom. Suppose the cake is cut into 64 smaller cubes, each measuring 1×1×1 inch, as shown below. How many of the small pieces will have icing on exactly two sides?

(A) 12 (B) 16 (C) 18 (D) 20 (E) 24

answer： D