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?
(A) 8 (B) 9 (C) 10 (D) 11 (E) 12
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