A 3 \times 3 \times 3 cube is formed by gluing together 27 standard cubical dice. (On a standard die, the sum of the numbers on any pair of opposite faces is 7.) The smallest possible sum of all the numbers showing on the surface of the 3 \times 3 \times 3 cube is
Answer Choices
A. 60
B. 72
C. 84
D. 90
E. 96