Answer: The correct option is (A) 0.75.
Step-by-step explanation: Given that the two right-angled triangles in the figure are similar. We are to find the ratio of the height to the base for the triangles.
In the first triangle,
height, h = 6 units and base, b = 8 units,
In the second triangles,
height, h' = 3 units and base, b' = 4 units.
Since the two triangles are similar, so the corresponding sides will be proportional.
We can see that

Hence, we can write

Therefore, the ratio of the height to the base of the triangles is 0.75.
Thus, (A) is the correct option.