A hollow sphere of inner radius 9 cm and outer radius 10 cm floats half submerged in a liquid of specific gravity 0.8. The density of the material of the sphere is

A

$$0.84\ \text{g cm}^{-3}$$

B

$$1.48\ \text{g cm}^{-3}$$

C

$$1.84\ \text{g cm}^{-3}$$

D

$$1.24\ \text{g cm}^{-3}$$