Well, we have linear terms (the heights and radii of the two cylinders) and cubic terms (the volume of the two cylinders). So, we need to cube the given ratio respective of their order.
2 -> to the power of 3 -> 2×2×2=8
3 -> to the power of 3 -> 3×3×3=27
Therefore, the ratio of the volumes of the two cylinders is 8:27. Your answer is D.