A3. From the nine points, you can choose three points in $\frac{9 \times 8 \times 7}{3 \times 2 \times 1}=84$ ways. But if three points lie on the same line, that does not form a triangle. This happens eight times, three times horizontally, three times vertically, and twice diagonally. So $84-8=76$ possibilities. (A).
A3. In the figure, there are nine grid points. How many triangles can you draw with the vertices at three of these nine points?
(A) 76
(B) 84
(C) 92
(D) 496
(E) 504