Answer: A
The heights of the two rings are 4h and 9h, and the radii are \(r_1\) and \(r_2\).
According to the given condition, the volumes of the rings are equal:
\[ \pi r_1^2 \times 4h = \pi r_2^2 \times 9h \] This simplifies to: \[ \frac{r_1^2}{r_2^2} = \frac{9h}{4h} \] \[ \frac{r_1}{r_2} = \sqrt{\frac{9}{4}} = \frac{3}{2} \] Therefore, the ratio of the radii \(r_1 : r_2 = 3 : 2\).
The heights of the two rings are 4h and 9h, and the radii are \(r_1\) and \(r_2\).
According to the given condition, the volumes of the rings are equal:
\[ \pi r_1^2 \times 4h = \pi r_2^2 \times 9h \] This simplifies to: \[ \frac{r_1^2}{r_2^2} = \frac{9h}{4h} \] \[ \frac{r_1}{r_2} = \sqrt{\frac{9}{4}} = \frac{3}{2} \] Therefore, the ratio of the radii \(r_1 : r_2 = 3 : 2\).