5. (10 points) There are two equilateral triangles of the same size, named Alpha and Beta. Each has a line segment connecting the midpoints of two sides, as shown in the figure. Alpha and Beta are positioned symmetrically left and right, but the line segments inside them are asymmetric. Starting from the positions shown in the figure, Alpha moves horizontally to the right until it overlaps with Beta and then leaves. At each position during the movement, the figure formed by Alpha and Beta contains several triangles. The position with the maximum number of triangles in the figure has ( ) triangles.
A. 9
B. 10
C. 11
D. 12
【Analysis】Draw all the cases and compare to find the figure with the most triangles, all the figures are as follows:
【Solution】According to the analysis of the problem, by observing the drawn figures, we can see that the 7th figure has the most triangles, with 11 triangles.

Therefore, the answer is: $C$.