The ratio of A to B is represented using the notation:
a : b
if a is the amount of A and b is the amount of B.
In this problem, A is triangles and B squares.
We can see from the image that the number of triangles is 2, and that the number of squares is 3.
So, we have:
a = 2
b = 3
Therefore, the ratio that represents the number of triangles to squares is 2:3.
Option A) is correct.