Let S be the set \{1,2,3, \ldots, 19\}. For a, b \in S, define a \succ b to mean that either 0<a-b \leq 9 or b-a>9. How many ordered triples (x, y, z) of elements of S have the property that x \succ y, y \succ z, and z \succ x ?
Answer Choices
A. 810
B. 855
C. 900
D. 950
E. 988