GAUSS8 2012 Problem 23

Different patterns can be created by shading exactly three of the nine small triangles shown, no two of which can share a side.\ Patterns that can be matched by rotations or by reflections are considered the same. For example, the following patterns are considered the same.\ How many different patterns can be created?

Answer Choices
A. 8
B. 9
C. 10
D. 11
E. 12