How many triangles are there in the following figure?

Counting by groups:

• Basic triangles: 4 inside the rectangle, 1 at the top-left, and 1 at the right = 6.

• Combined triangles: 4 larger triangles formed inside the rectangle by combining adjacent small triangles, plus 2 larger side triangles = 6.

• Outer triangle: The complete boundary triangle = 1.

Total: 6 + 6 + 1 = 13

Final answer: Option C