Answer: D) 9:1
Explanation:
The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding altitudes (heights).
If the ratio of the altitude of triangle A to the altitude of triangle B is 3:1, then the ratio of the areas of triangle A to triangle B will be (3^2):(1^2), which simplifies to 9:1.
So, the correct answer is:
D) 9:1